UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C.  20549
FORM 10-Q
(Mark One)
xQUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934
For the quarterly period ended JuneSept. 30, 2018
or
¨TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934
Commission File Number: 001-3280
Public Service Company of Colorado
(Exact name of registrant as specified in its charter)
Colorado 84-0296600
(State or other jurisdiction of incorporation or organization) (I.R.S. Employer Identification No.)
   
1800 Larimer, Suite 1100  
Denver, Colorado 80202
(Address of principal executive offices) (Zip Code)
(303) 571-7511
(Registrant’s telephone number, including area code)

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. x Yes ¨ No

Indicate by check mark whether the registrant has submitted electronically and posted on its corporate Web site, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 and Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files). x Yes ¨ No

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, smaller reporting company or an emerging growth company.  See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.
Large accelerated filer ¨
 
Accelerated filer ¨
   
Non-accelerated filer x
 
Smaller reporting company ¨
(Do not check if smaller reporting company) 
 Emerging growth company ¨
If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ¨

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). ¨ Yes x No

Indicate the number of shares outstanding of each of the issuer’s classes of common stock, as of the latest practicable date.
Class July 27,Oct. 26, 2018
Common Stock, $0.01 par value 100 shares

Public Service Company of Colorado meets the conditions set forth in General Instruction H (1) (a) and (b) of Form 10-Q and is therefore filing this Form 10-Q with the reduced disclosure format specified in General Instruction H (2) to such Form 10-Q.
     

TABLE OF CONTENTS

PART I — FINANCIAL INFORMATION
 
   
Item l —
Item 2 —
Item 4 —
   
PART II — OTHER INFORMATION
 
   
Item 1 —
Item 1A —
Item 6 —
   

  
Certifications Pursuant to Section 3021
Certifications Pursuant to Section 9061
Statement Pursuant to Private Litigation1

This Form 10-Q is filed by Public Service Company of Colorado, a Colorado corporation (PSCo). PSCo is a wholly owned subsidiary of Xcel Energy Inc. Xcel Energy Inc. wholly owns the following subsidiaries: Northern States Power Company, a Minnesota corporation (NSP-Minnesota); Northern States Power Company, a Wisconsin corporation (NSP-Wisconsin); PSCo; and Southwestern Public Service Company, a New Mexico corporation (SPS). NSP-Minnesota, NSP-Wisconsin, PSCo and SPS are also referred to collectively as utility subsidiaries. Additional information on Xcel Energy Inc. and its subsidiaries (collectively, Xcel Energy) is available on various filings with the Securities and Exchange Commission (SEC).

PART I — FINANCIAL INFORMATION

Item 1FINANCIAL STATEMENTS

PUBLIC SERVICE CO. OF COLORADO AND SUBSIDIARIES
CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED)
(amounts in thousands)
Three Months Ended June 30 Six Months Ended June 30Three Months Ended Sept. 30 Nine Months Ended Sept. 30
2018 2017 2018 20172018 2017 2018 2017
Operating revenues              
Electric$716,195
 $729,920
 $1,414,469
 $1,441,308
$894,786
 $877,604
 $2,309,255
 $2,318,912
Natural gas186,661
 192,777
 550,647
 548,913
157,205
 142,389
 707,852
 691,302
Steam and other9,010
 8,219
 20,048
 21,229
8,688
 10,300
 28,736
 31,529
Total operating revenues911,866
 930,916
 1,985,164
 2,011,450
1,060,679
 1,030,293
 3,045,843
 3,041,743
              
Operating expenses 
  
     
  
    
Electric fuel and purchased power271,891
 279,522
 553,061
 568,349
288,589
 288,997
 841,650
 857,346
Cost of natural gas sold and transported58,559
 70,258
 249,824
 266,660
32,310
 37,243
 282,134
 303,903
Cost of sales — steam and other3,664
 3,507
 7,540
 7,893
3,327
 4,098
 10,867
 11,991
Operating and maintenance expenses188,991
 187,394
 372,066
 372,482
201,390
 173,392
 573,456
 545,874
Demand side management expenses33,202
 29,928
 65,954
 58,032
39,391
 34,520
 105,345
 92,552
Depreciation and amortization116,553
 117,513
 238,160
 232,507
167,961
 118,289
 406,121
 350,796
Taxes (other than income taxes)49,743
 49,470
 102,400
 99,268
50,820
 47,213
 153,220
 146,481
Total operating expenses722,603
 737,592
 1,589,005
 1,605,191
783,788
 703,752
 2,372,793
 2,308,943
              
Operating income189,263
 193,324
 396,159
 406,259
276,891
 326,541
 673,050
 732,800
              
Other income, net799
 1,319
 1,030
 4,523
1,399
 1,023
 2,429
 5,546
Allowance for funds used during construction — equity13,555
 6,341
 24,499
 10,949
16,353
 8,642
 40,851
 19,591
              
Interest charges and financing costs 
  
     
  
    
Interest charges — includes other financing costs of $1,601 and $1,543, $3,173, and $3,064 respectively51,221
 46,424
 101,142
 92,306
Interest charges — includes other financing costs of $1,682 and $1,605, $4,855, and $4,669 respectively53,182
 49,097
 154,324
 141,403
Allowance for funds used during construction — debt(5,205) (2,438) (9,786) (4,344)(6,370) (3,266) (16,156) (7,610)
Total interest charges and financing costs46,016
 43,986
 91,356
 87,962
46,812
 45,831
 138,168
 133,793
              
Income before income taxes157,601
 156,998
 330,332
 333,769
247,831
 290,375
 578,162
 624,144
Income taxes35,305
 56,411
 74,314
 121,636
40,719
 104,298
 115,033
 225,934
Net income$122,296
 $100,587
 $256,018
 $212,133
$207,112
 $186,077
 $463,129
 $398,210
 
See Notes to Consolidated Financial Statements

PUBLIC SERVICE CO. OF COLORADO AND SUBSIDIARIES
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED)
(amounts in thousands)
 Three Months Ended June 30 Six Months Ended June 30 Three Months Ended Sept. 30 Nine Months Ended Sept. 30
 2018 2017 2018 2017 2018 2017 2018 2017
Net income $122,296
 $100,587
 $256,018
 $212,133
 $207,112
 $186,077
 $463,129
 $398,210
                
Other comprehensive income (loss)      
  
      
  
                
Pension and retiree medical benefits:                
Amortization of losses included in net periodic benefit cost, net of tax of $0, $1, $0, and $2, respectively 2
 1
 4
 2
Net pension and retiree medical losses arising during the period, net of tax of $(50), $0, $(50) and $0, respectively (153) 
 (153) 
Amortization of losses included in net periodic benefit cost, net of tax of $51, $1, $51, and $3, respectively 155
 1
 159
 3
 2
 1
 6
 3
                
Derivative instruments:      
  
      
  
Reclassification of losses to net income, net of tax of $99, $153, $197 and $305, respectively 303
 250
 603
 496
Reclassification of losses to net income, net of tax of $97, $150, $294 and $455, respectively 310
 257
 913
 753
                
Other comprehensive income 305
 251
 607
 498
 312
 258
 919
 756
Comprehensive income $122,601
 $100,838
 $256,625
 $212,631
 $207,424
 $186,335
 $464,048
 $398,966

See Notes to Consolidated Financial Statements


PUBLIC SERVICE CO. OF COLORADO AND SUBSIDIARIES
CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED)
(amounts in thousands)
Six Months Ended June 30Nine Months Ended Sept. 30
2018 20172018 2017
Operating activities      
Net income$256,018
 $212,133
$463,129
 $398,210
Adjustments to reconcile net income to cash provided by operating activities: 
  
 
  
Depreciation and amortization240,577
 234,143
409,836
 353,653
Demand side management program amortization
 672


 

Deferred income taxes25,579
 126,252
66,563
 223,121
Amortization of investment tax credits(1,399) (1,401)(2,099) (2,102)
Allowance for equity funds used during construction(24,499) (10,949)(40,851) (19,591)
Net realized and unrealized hedging and derivative transactions(1,917) 1,951
(9,852) 907
Other1
 
1
 661
Changes in operating assets and liabilities: 
  
 
  
Accounts receivable21,991
 24,042
(737) 4,431
Accrued unbilled revenues66,497
 81,649
60,079
 74,918
Inventories44,769
 38,452
13,557
 (250)
Prepayments and other1,522
 (4,837)12,633
 11,717
Accounts payable(22,097) (51,894)25,303
 (53,706)
Net regulatory assets and liabilities30,405
 (2,499)(23,604) (28,594)
Other current liabilities(119,132) (67,418)(87,867) (40,789)
Pension and other employee benefit obligations(27,457) (16,543)(28,958) (16,691)
Change in other noncurrent assets3,880
 (717)6,551
 (1,149)
Change in other noncurrent liabilities(14,546) (228)(26,296) (1,916)
Net cash provided by operating activities480,192
 562,808
837,388
 902,830
      
Investing activities 
  
 
  
Utility capital/construction expenditures(825,463) (609,369)(1,231,585) (995,680)
Allowance for equity funds used during construction24,499
 10,949
40,851
 19,591
Investments in utility money pool arrangement(198,000) (777,000)(578,000) (659,000)
Repayments from utility money pool arrangement56,000
 625,000
575,000
 609,000
Other, net
 (657)
 (657)
Net cash used in investing activities(942,964) (751,077)(1,193,734) (1,026,746)
      
Financing activities 
  
 
  
Repayments of short-term borrowings, net
 (129,000)
 (129,000)
Borrowings under utility money pool arrangement526,000
 40,000
526,000
 40,000
Repayments under utility money pool arrangement(526,000) (40,000)(526,000) (40,000)
Proceeds from issuance of long-term debt692,697
 394,611
691,439
 393,795
Repayments of long-term debt(300,000) 
Capital contributions from parent216,508
 82,475
246,829
 158,080
Dividends paid to parent(171,546) (161,312)(271,884) (245,291)
Other(118) (110)(118) (110)
Net cash provided by financing activities737,541
 186,664
366,266
 177,474
      
Net change in cash and cash equivalents274,769
 (1,605)9,920
 53,558
Cash and cash equivalents at beginning of period7,513
 5,926
7,513
 5,926
Cash and cash equivalents at end of period$282,282
 $4,321
$17,433
 $59,484
      
Supplemental disclosure of cash flow information: 
  
 
  
Cash paid for interest (net of amounts capitalized)$(88,912) $(84,452)$(145,251) $(145,461)
Cash paid for income taxes, net(96,448) (12,195)(86,418) (7,752)
Supplemental disclosure of non-cash investing transactions: 
  
 
  
Property, plant and equipment additions in accounts payable$131,823
 $103,774
$134,994
 $133,933

See Notes to Consolidated Financial Statements

PUBLIC SERVICE CO. OF COLORADO AND SUBSIDIARIES
CONSOLIDATED BALANCE SHEETS (UNAUDITED)
(amounts in thousands, except share and per share data)
June 30, 2018 Dec. 31, 2017Sept. 30, 2018 Dec. 31, 2017
Assets      
Current assets      
Cash and cash equivalents$282,282
 $7,513
$17,433
 $7,513
Accounts receivable, net272,293
 294,403
299,980
 294,403
Accounts receivable from affiliates38,650
 14,719
8,605
 14,719
Investments in utility money pool arrangement162,000
 20,000
23,000
 20,000
Accrued unbilled revenues229,304
 295,801
235,722
 295,801
Inventories169,720
 214,489
187,412
 214,489
Regulatory assets76,419
 77,337
111,996
 77,337
Derivative instruments5,340
 3,197
16,562
 3,197
Prepayments and other39,237
 35,720
28,207
 35,720
Total current assets1,275,245
 963,179
928,917
 963,179
      
Property, plant and equipment, net14,541,078
 14,025,751
14,839,033
 14,025,751
      
Other assets 
  
 
  
Regulatory assets980,811
 950,258
987,696
 950,258
Derivative instruments2,716
 1,009
3,688
 1,009
Other23,259
 27,429
20,542
 27,429
Total other assets1,006,786
 978,696
1,011,926
 978,696
Total assets$16,823,109
 $15,967,626
$16,779,876
 $15,967,626
      
Liabilities and Equity 
  
 
  
Current liabilities 
  
 
  
Current portion of long-term debt$705,869
 $305,577
$406,021
 $305,577
Accounts payable433,822
 492,829
467,173
 492,829
Accounts payable to affiliates38,395
 58,749
48,220
 58,749
Regulatory liabilities95,053
 66,126
55,587
 66,126
Taxes accrued108,812
 222,517
155,131
 222,517
Accrued interest49,803
 48,552
38,881
 48,552
Dividends payable to parent100,338
 76,195
103,470
 76,195
Derivative instruments5,428
 7,348
8,918
 7,348
Other92,583
 92,333
88,500
 92,333
Total current liabilities1,630,103
 1,370,226
1,371,901
 1,370,226
      
Deferred credits and other liabilities 
  
 
  
Deferred income taxes1,678,207
 1,644,476
1,732,686
 1,644,476
Deferred investment tax credits26,459
 27,858
25,759
 27,858
Regulatory liabilities1,926,944
 1,933,488
1,982,649
 1,933,488
Asset retirement obligations355,028
 347,769
358,715
 347,769
Derivative instruments2,471
 3,468
3,156
 3,468
Customer advances170,659
 162,614
166,325
 162,614
Pension and employee benefit obligations260,012
 287,783
258,509
 287,783
Other49,454
 58,923
49,028
 58,923
Total deferred credits and other liabilities4,469,234
 4,466,379
4,576,827
 4,466,379
      
Commitments and contingencies

 



 

Capitalization 
  
 
  
Long-term debt4,594,193
 4,302,698
4,592,382
 4,302,698
Common stock — 100 shares authorized at $0.01 par value; 100 shares
outstanding at June 30, 2018 and Dec. 31, 2017, respectively

 
Common stock — 100 shares authorized at $0.01 par value; 100 shares
outstanding at Sept. 30, 2018 and Dec. 31, 2017, respectively

 
Additional paid in capital4,273,146
 4,032,826
4,278,380
 4,032,826
Retained earnings1,882,558
 1,822,229
1,986,199
 1,822,229
Accumulated other comprehensive loss(26,125) (26,732)(25,813) (26,732)
Total common stockholder’s equity6,129,579
 5,828,323
6,238,766
 5,828,323
Total liabilities and equity$16,823,109
 $15,967,626
$16,779,876
 $15,967,626

See Notes to Consolidated Financial Statements

PUBLIC SERVICE CO. OF COLORADO AND SUBSIDIARIES
Notes to Consolidated Financial Statements (UNAUDITED)

In the opinion of management, the accompanying unaudited consolidated financial statements contain all adjustments necessary to present fairly, in accordance with accounting principles generally accepted in the United States of America (GAAP), the financial position of PSCo and its subsidiaries as of JuneSept. 30, 2018 and Dec. 31, 2017; the results of its operations, including the components of net income and comprehensive income, for the three and sixnine months ended JuneSept. 30, 2018 and 2017; and its cash flows for the sixnine months ended JuneSept. 30, 2018 and 2017. All adjustments are of a normal, recurring nature, except as otherwise disclosed. Management has also evaluated the impact of events occurring after JuneSept. 30, 2018 up to the date of issuance of these consolidated financial statements. These statements contain all necessary adjustments and disclosures resulting from that evaluation. The Dec. 31, 2017 balance sheet information has been derived from the audited 2017 consolidated financial statements included in the PSCo Annual Report on Form 10-K for the year ended Dec. 31, 2017. These notes to the consolidated financial statements have been prepared pursuant to the rules and regulations of the SEC for Quarterly Reports on Form 10-Q. Certain information and note disclosures normally included in financial statements prepared in accordance with GAAP on an annual basis have been condensed or omitted pursuant to such rules and regulations. For further information, refer to the consolidated financial statements and notes thereto, included in the PSCo Annual Report on Form 10-K for the year ended Dec. 31, 2017, filed with the SEC on Feb. 23, 2018. Due to the seasonality of PSCo’s electric and natural gas sales, interim results are not necessarily an appropriate base from which to project annual results.

1.Summary of Significant Accounting Policies

The significant accounting policies set forth in Note 1 to the consolidated financial statements in the PSCo Annual Report on Form 10-K for the year ended Dec. 31, 2017, appropriately represent, in all material respects, the current status of accounting policies and are incorporated herein by reference.

2.Accounting Pronouncements

Recently Issued

Leases —In In February 2016, the Financial Accounting Standards Board (FASB) issued Leases, Topic 842 (Accounting Standards Update (ASU) No. 2016-02), which for lessees requires balance sheet recognition of right-of-use assets and lease liabilities for most leases. This guidance will be effective for interim and annual reporting periods beginning after Dec. 15, 2018. PSCo has not yet fully determined the impacts of implementation. However, adoption is expected toAdoption will occur on Jan. 1, 2019 utilizing the practical expedients provided by the standard and proposedincluded in Targeted Improvements, Topic 842 (Proposed (ASU 2018-200)No. 2018-11). On Jan. 1, 2019, agreements consideredhistorically disclosed as operating leases for the use of office space,real estate, equipment and natural gas storage assets, as well as certain fossil-fueled generating facilities operated under purchased power agreements (PPAs) for fossil-fueled generating facilities are expected to be recognized on the consolidated balance sheet. Other than first-time recognition of these types of operating leases on the consolidated balance sheet, the implementation is not expected to have a significant impact on PSCo’s consolidated financial statements.

Recently Adopted

Revenue Recognition In May 2014, the FASB issued Revenue from Contracts with Customers, Topic 606 (ASU No. 2014-09), which provides a new framework for the recognition of revenue. PSCo implemented the guidance on a modified retrospective basis on Jan. 1, 2018. Results for reporting periods beginning after Dec. 31, 2017 are presented in accordance with Topic 606, while prior period results have not been adjusted and continue to be reported in accordance with prior accounting guidance. Other than increased disclosures regarding revenues related to contracts with customers, the implementation did not have a significantmaterial impact on PSCo’s consolidated financial statements. For related disclosures, see Note 13 to the consolidated financial statements.

Classification and Measurement of Financial Instruments — In January 2016, the FASB issued Recognition and Measurement of Financial Assets and Financial Liabilities, Subtopic 825-10 (ASU No. 2016-01), which eliminated the available-for-sale classification for marketable equity securities and also replaced the cost method of accounting for non-marketable equity securities with a model for recognizing impairments and observable price changes. Under the new standard, other than when the consolidation or equity method of accounting is utilized, changes in the fair value of equity securities are recognized in earnings. PSCo implemented the guidance on Jan. 1, 2018 and the implementation did not have a material impact on its consolidated financial statements.

Presentation of Net Periodic Benefit Cost — In March 2017, the FASB issued Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost, Topic 715 (ASU No. 2017-07), which establishes that only the service cost element of pension cost may be presented as a component of operating income in the income statement. Also under the guidance, only the service cost component of pension cost is eligible for capitalization. As a result of the application of accounting principles for rate regulated entities, a similar amount of pension cost, including non-service components, will be recognized consistent with the historical ratemaking treatment, and the impacts of adoption will be limited to changes in classification of non-service costs in the consolidated statement of income. PSCo implemented the new guidance on Jan. 1, 2018, and as a result, $1.0$0.5 million and $1.5 million of pension costs were retrospectively reclassified from operating and maintenance expenses to other income, net on the consolidated income statement for the sixthree and nine months ended JuneSept. 30, 2017.2017, respectively. Under a practical expedient permitted by the standard, PSCo used benefit cost amounts disclosed for prior periods as the basis for retrospective application.

3.Selected Balance Sheet Data
(Thousands of Dollars) June 30, 2018 Dec. 31, 2017 Sept. 30, 2018 Dec. 31, 2017
Accounts receivable, net        
Accounts receivable $290,832
 $314,009
 $320,572
 $314,009
Less allowance for bad debts (18,539) (19,606) (20,592) (19,606)
 $272,293
 $294,403
 $299,980
 $294,403
(Thousands of Dollars) June 30, 2018 Dec. 31, 2017 Sept. 30, 2018 Dec. 31, 2017
Inventories        
Materials and supplies $70,940
 $68,940
 $58,198
 $68,940
Fuel 62,532
 73,893
 62,409
 73,893
Natural gas 36,248
 71,656
 66,805
 71,656
 $169,720
 $214,489
 $187,412
 $214,489
(Thousands of Dollars) June 30, 2018 Dec. 31, 2017 Sept. 30, 2018 Dec. 31, 2017
Property, plant and equipment, net        
Electric plant $12,780,963
 $12,627,592
 $12,401,598
 $12,627,592
Natural gas plant 4,211,977
 4,102,075
 4,269,700
 4,102,075
Common and other property 1,040,638
 1,022,333
 1,046,991
 1,022,333
Plant to be retired (a)
 10,306
 10,949
 337,087
 10,949
Construction work in progress 1,444,140
 1,014,338
 1,575,102
 1,014,338
Total property, plant and equipment 19,488,024
 18,777,287
 19,630,478
 18,777,287
Less accumulated depreciation (4,946,946) (4,751,536) (4,791,445) (4,751,536)
 $14,541,078
 $14,025,751
 $14,839,033
 $14,025,751

(a) 
In the third quarter of 2018, the Colorado Public Utilities Commission (CPUC) approved early retirement of PSCo’s Comanche Units 1, 2 and shared Common plant in approximately 2022, 2025 and 2025, respectively. PSCo also expects Craig Unit 1 to be early retired in approximately 2025. In the third quarter of 2017, PSCo early retired Valmont Unit 5 and converted Cherokee Unit 4 from a coal-fueled generating facility to natural gas. PSCo also expects Craig Unit 1 to be early retired in approximately 2025. Amounts are presented net of accumulated depreciation.

4.Income Taxes

Except to the extent noted below, Note 7 to the consolidated financial statements included in PSCo’s Annual Report on Form 10-K for the year ended Dec. 31, 2017 appropriately represents, in all material respects, the current status of other income tax matters, and are incorporated herein by reference.


Total income tax expense from operations differs from the amount computed by applying the statutory federal income tax rate to income before income tax expense. The following reconciles such differences:
 Six Months Ended June 30 Nine Months Ended Sept. 30
 2018 2017 2018 2017
Federal statutory rate 21.0 % 35.0 % 21.0 % 35.0 %
State tax, net of federal tax effect 3.7
 3.0
State tax (net of federal tax effect) 3.7
 3.0
Increases (decreases) in tax from: 
 
 
 
Regulatory differences - ARAM (a)
 (3.2) (0.1) (2.5) 
Regulatory differences - ARAM deferral (b)
 3.0
 
 2.2
 
Regulatory differences - reversal of prior quarters' ARAM deferral (b)
 (1.5) 
Regulatory differences - other utility plant items (1.3) (0.9) (1.3) (1.0)
Tax credits, net of federal income tax expense (1.0) (0.7)
Other, net 0.3
 0.1
Tax credits (net of federal income tax expense) (0.9) (0.8)
Other (net) (0.8) 
Effective income tax rate 22.5 % 36.4 % 19.9 % 36.2 %
(a)  
The average rate assumption method (ARAM); a method to flow back excess deferred taxes to customers.
(b)
ARAM has been deferred when regulatory treatment has not been established. As we receivePSCO received direction from ourits regulatory commissionscommission regarding the return of excess deferred taxes (to ourto customers, resulting from the Tax Cuts and Jobs ActARAM deferral was reversed. This resulted in a reduction to tax expense with a corresponding reduction to revenue.
(TCJA)), the ARAM deferral may decrease during the year, which would result in a reduction to tax expense with a corresponding reduction to revenue.

Federal Audits  PSCO is a member of the Xcel Energy affiliated group that files a consolidated federal income tax return. The statute of limitations applicable to Xcel Energy’s federal income tax returns expire as follows:
Tax Year(s) Expiration
2009 - 2011December 2018
2012 - 2014 October 2019
2015 September 2019
2016 September 2020

In 2012, the Internal Revenue Service (IRS) commenced an examination of tax years 2010 and 2011, including the 2009 carryback claim. The IRS proposed an adjustment to the federal tax loss carryback claimsIn 2017 Xcel Energy and in 2015, the IRS forwarded the issue to the Office of Appeals (Appeals). In 2017 Xcel Energy and Appeals reached an agreement and the benefit related to the agreed upon portions was recognized. PSCo did not accrue any income tax benefit related to this adjustment. In the second quarter of 2018, the Joint Committee on Taxation completed its review and took no exception to the agreement. As a result, the remaining unrecognized tax benefit was released and recorded as a payable to the IRS.

In the third quarter of 2015, the IRS commenced an examination of tax years 2012 and 2013. In the third quarter of 2017, the IRS concluded the audit of tax years 2012 and 2013 and proposed an adjustment that would impact Xcel Energy’s net operating loss (NOL) and effective tax rate (ETR). After evaluating the proposed adjustment Xcel Energy filed a protest with the IRS. As of JuneSept. 30, 2018, the case has been forwarded to Appeals and Xcel Energy has recognized its best estimate of income tax expense that will result from a final resolution of this issue; however, the outcome and timing of a resolution is unknown.

State Audits — PSCo is a member of the Xcel Energy affiliated group that files consolidated state income tax returns. As of JuneSept. 30, 2018, PSCo’s earliest open tax year that is subject to examination by state taxing authorities under applicable statutes of limitations is 2009. There are currently no state income tax audits in progress.


Unrecognized Benefits The unrecognized tax benefit balance includes permanent tax positions, which if recognized would affect the annual ETR. In addition, the unrecognized tax benefit balance includes temporary tax positions for which the ultimate deductibility is highly certain but for which there is uncertainty about the timing of such deductibility. A change in the period of deductibility would not affect the ETR but would accelerate the payment of cash to the taxing authority to an earlier period.

A reconciliation of the amount of unrecognized tax benefit is as follows:
(Millions of Dollars) June 30, 2018 Dec. 31, 2017 Sept. 30, 2018 Dec. 31, 2017
Unrecognized tax benefit — Permanent tax positions $4.4
 $4.0
 $5.1
 $4.0
Unrecognized tax benefit — Temporary tax positions 5.0
 6.1
 4.9
 6.1
Total unrecognized tax benefit $9.4
 $10.1
 $10.0
 $10.1


The unrecognized tax benefit amounts were reduced by the tax benefits associated with NOL and tax credit carryforwards. The amounts of tax benefits associated with NOL and tax credit carryforwards are as follows:
(Millions of Dollars) June 30, 2018 Dec. 31, 2017 Sept. 30, 2018 Dec. 31, 2017
NOL and tax credit carryforwards $(4.7) $(4.0) $(5.5) $(4.0)

It is reasonably possible that PSCo’s amount of unrecognized tax benefits could significantly change in the next 12 months as the IRS Appeals progresses and the IRS and state audits resume. As the IRS Appeals progresses and the IRS audit resumes, it is reasonably possible that the amount of unrecognized tax benefit could decrease up to approximately $8 million.

The payablePayables for interest related to unrecognized tax benefits is partially offset by the interest benefit associated with NOL and tax credit carryforwards. The payables for interest related to unrecognized tax benefits at June 30, 2018, and Dec. 31, 2017 were not material. Nomaterial and no amounts were accrued for penalties related to unrecognized tax benefits as of JuneSept. 30, 2018 or Dec. 31, 2017.

5.Rate Matters

Except to the extent noted below, the circumstances set forth in Note 11 to the consolidated financial statements included in PSCo’s Annual Report on Form 10-K for the year ended Dec. 31, 2017 and in Note 5 to the consolidated financial statements to PSCo’s Quarterly ReportReports on Form 10-Q for the quarterly periodperiods ended March 31, 2018 and June 30, 2018, appropriately represent, in all material respects, the current status of other rate matters, and are incorporated herein by reference.

Tax Reform Regulatory Proceedings

The specific impacts of the TCJA on customer rates are subject to regulatory approval. EachThe following details the status of the states in Xcel Energy’s service areas, including Colorado, have opened dockets to address the impacts of the TCJA.regulatory decisions.

Colorado Natural Gas — In February 2018, the administrative law judge (ALJ) approvedrecommended approval of PSCo and the Colorado Public Utilities Commission (CPUC)CPUC Staff’s TCJA settlement agreement which includesincluded a $20 million reduction to provisional rates effective March 1, 2018. A finalIn September 2018, PSCo submitted a TCJA true-up would provide customersfiling and revised its TCJA benefit estimate to $24 million and requested an equity ratio of 56 percent to offset the full net benefitnegative impact of the TCJA on credit metrics. A decision is expected in the fourth quarter of 2018. The true-up of the estimated TCJA benefit is expected to be retroactive to January 2018.

Colorado Electric — In April 2018, PSCo, the CPUC Staff, and the Office of Consumer Counsel (OCC) filed a TCJA settlement agreement for 2018 that recommendedincluded a customer refund of $42 million in 2018, with the remainder of the $59 million of TCJA benefits to be used to accelerate the amortization of an existing prepaid pension asset.  In June 2018, the CPUC approved the customer refund of $42 million, effective June 1, 2018. The CPUC setmillion. In October 2018, the decision regarding the remainderaccelerated amortization of the $59prepaid pension asset was effective by operation of law. For 2019, the expected customer refund is estimated to be $67 million, for hearing before an ALJ. Revisionsand amortization of the prepaid pension asset is estimated to be $34 million. Impacts of the TCJA settlement willfor 2020 and beyond are expected to be addressed in a future electric rate case.


Pending Regulatory Proceedings — CPUC

Colorado 2017 Multi-Year Electric Rate Case — In October 2017, PSCo filed a multi-year request with the CPUC seeking to increase electric rates approximately $245 million over four years. The request was based on forecast test years (FTY), a 10.0 percent return on equity (ROE) and an equity ratio of 55.25 percent. Interim rates, subject to refund and interest, were to be effective on June 1, 2018.
Revenue Request (Millions of Dollars) 2018 2019 2020 2021 Total
Revenue request $74
 $75
 $60
 $36
 $245
Clean Air Clean Jobs Act (CACJA) rider conversion to base rates 90
 
 
 
 90
Transmission Cost Adjustment (TCA) rider conversion to base rates 43
 
 
 
 43
  Total $207
 $75
 $60
 $36
 $378
           
Expected year-end rate base (billions of dollars) $6.8
 $7.1
 $7.3
 $7.4
  
In March 2018, PSCo, CPUC Staff and OCC reached a settlement and filed a motion with the CPUC requesting changes to the procedural schedule and scope of the electric case, which included delaying the implementation of provisional rates from June 2018 to January 2019 and requiring PSCo to file updated test year information for 2019 through 2021 which included the impacts of TCJA. In April 2018, the CPUC denied the motion on procedural grounds and dismissed the electric rate case.

Colorado 2017 Multi-Year Natural Gas Rate Case — In June 2017, PSCo filed a multi-year request with the CPUC seeking to increase retail natural gas rates approximately $139 million over three years. The request detailed below, was based on FTYs,forward test years, a 10.0 percent ROE and an equity ratio of 55.25 percent.
Revenue Request (Millions of Dollars) 2018 2019 2020 Total
Revenue request $63
 $33
 $43
 $139
Pipeline System Integrity Adjustment (PSIA) rider conversion to base rates (a)
 
 94
 
 94
Total $63
 $127
 $43
 $233
         
Expected year-end rate base (billions of dollars) (b)
 $1.5
 $2.3
 $2.4
  
(a)
The roll-in of PSIA rider revenue into base rates will not have an impact on customer bills or revenue as these costs are already being recovered through the rider. The recovery of incremental PSIA related investments in 2019 and 2020 are included in the base rate request.
(b)
The additional rate base in 2019 predominantly reflects the roll-in of capital associated with the PSIA rider.

In FebruaryAugust 2018, the administrative law judge (ALJ) approved a TCJA settlement agreement between PSCo and the CPUC Staff, which reduced provisional rates by $20 million, based on a preliminary TCJA estimate of $29 million. The settlement remains subject to CPUC approval. The impact of the TCJA will be trued-up later in 2018. Annualized provisional rates of approximately $43 million were effective March 1, 2018.

In May 2018, the ALJ issued an interim recommended decision which would result in a 2018 overall rate increasethat included application of approximately $46 million, prior to the impact of the TCJA. The estimated rate increase reflects a 2016 HTYhistoric test year (HTY), with a 13-month average rate base, of $1.6 billion, aan ROE of 9.35 percent, and an equity ratio of 54.2 percent.
On July 12, 2018, the CPUC deliberated and approved several of the ALJ’s recommendations including application of a 2016 HTY, with a 13-month average rate base, and an ROE of 9.35 percent.  The CPUC adjusted the equity ratio to 54.6 percent and provided no return on the prepaid pension and retiree medical asset.  With these adjustments, the total rate increase, prior to TCJA impacts, would be $47 million.


The estimated impact of PSCo filed an interim rehearing request to preserve its rights and the CPUC’s decision is presented below:
(Millions of Dollars) Estimated Impact of the CPUC’s Decision
Filed 2018 revenue request based on a FTY $63
Impact of the change in test year 5
PSCo’s deficiency based on a 2016 HTY - year-end rate base 68
   
Adjustments:  
  ROE at 9.35 percent (9)
Equity ratio of 54.6 percent (2)
Change in amortization period for certain regulatory assets, including a debt return (6)
Loss of return on prepaid pension and retiree medical (4)
Change from 2016 year-end to average rate base (5)
Other, net 5
Total adjustments (21)
   
Total rate increase, prior to the TCJA impacts 
 $47
CPUC decided that any reconsideration can be brought after a final order incorporating TCJA impacts. The CPUC is expected to issue its order on the natural gas rate case inand the third quarter of 2018. The CPUC is expected to issue a final decision withrelated to the impacts of the TCJA later in the fourth quarter of 2018.

Provisional rates, subject to refund, were implemented on Jan. 1, 2018. A current liability which represents PSCo’s best estimate of a refund obligation associated with provisional rates was recorded as of June 30, 2018.

PSIA Rider
In JuneOctober 2018, PSCo, CPUC Staff, and the OCC filed for an extensiona settlement agreement to extend the PSIA rider through 2020. PSCo requested an expedited decision by Nov. 15, 2018. PSCo also requested authorization to roll-in recovery of costs in the current PSIA rider into base rates effective Jan. 1, 2019, if the2021. The CPUC rejects the proposed PSIA extension or failsis expected to rule on the request bysettlement in the endfourth quarter of 2018.

Additionally, PSCo reduced PSIA revenues by approximately $8 million for 2018 for the impact of the TCJA, effective May 1, 2018. PSIA revenues are subject to the CPUC approved PSIA rider true-up process.

6.Commitments and Contingencies

Except to the extent noted below and in Note 5 to the consolidated financial statements, the circumstances set forth in Notes 11 and 12 to the consolidated financial statements included in PSCo’s Annual Report on Form 10-K for the year ended Dec. 31, 2017 and in Notes 5 and 6 to PSCo’s Quarterly ReportReports on Form 10-Q for the quarterly periodperiods ended March 31, 2018 and June 30, 2018, appropriately represent, in all material respects, the current status of commitments and contingent liabilities and are incorporated herein by reference. The following include commitments, contingencies and unresolved contingencies that are material to PSCo’s financial position.

PPAs

PSCo purchases power from independent power producing entities that own natural gas fueled power plants for which PSCo is required to reimburse natural gas fuel costs, or to participate in tolling arrangements under which PSCo procures the natural gas required to produce the energy that it purchases. These specific PPAs create a variable interest in the associated independent power producing entity.

PSCo had approximately 1,571 Megawatts (MW) of capacity under long-term PPAs as of JuneSept. 30, 2018 and Dec. 31, 2017, with entities that have been determined to be variable interest entities. PSCo has concluded that these entities are not required to be consolidated in its consolidated financial statements because it does not have the power to direct the activities that most significantly impact the entities’ economic performance. These agreements have various expiration dates through 2032.

Environmental Contingencies

Manufactured Gas Plant (MGP), Landfill or Disposal Sites — PSCo is currently involved in investigating and/or remediating several MGP, landfill or other disposal sites. PSCo has identified foursites where contamination is present and where investigation and/or remediation activities are currently underway. Other parties may have responsibility for some portion of the investigation and/or remediation activities. PSCo anticipates that these investigation or remediation activities will continue through at least 2018.2019. PSCo accrued $2$1 million as of JuneSept. 30, 2018 and an immaterial amount as of Dec. 31, 2017, for these sites. There may be insurance recovery and/or recovery from other potentially responsible parties that will offset any costs incurred. PSCo anticipates that any amounts spent will be fully recovered from customers.

Environmental Requirements

AirWater and Waste
RevisionsCoal Ash Regulation — PSCo’s operations are subject to the National Ambient Air Quality Standard (NAAQS)federal and state laws that impose requirements for Ozone -handling, storage, treatment and disposal of solid waste. In 2015, the EPA revisedUnited States Environmental Protection Agency published a final rule regulating the NAAQS for ozone by loweringmanagement, storage, and disposal of coal combustion residuals (CCRs) as a nonhazardous waste (CCR Rule).

Under the eight-hour standard from 75 parts per billion (ppb)CCR Rule, utilities are required to 70 ppb.complete certain groundwater sampling around their CCR landfills and surface impoundments. PSCo meets the 2015 ozone standard in all areashas identified at least one site where its generating units operate, except for the Denver Metropolitan Area. PSCo’s retirementthere are impoundments and/or landfills present and where a statistically significant increase of its coal fired plantscertain constituents exist in the Denver non-attainment area helped Colorado’s plan to mitigate non-attainment. In June 2018,groundwater. However, at that location, closure activities are already underway. PSCo is currently conducting additional groundwater sampling and will evaluate whether corrective action is required at any CCR landfills or surface impoundments. Until PSCo completes additional groundwater sampling, it is uncertain what impact, if any, there will be on the EPA designated the parts of the Denver Metropolitan Areaoperations, financial position or cash flows. PSCo believes that currently do not attain the 2008 ozone standards as also not attaining the more stringent 2015 ozone standard. Colorado will continue to consider further reductions that are available in the non-attainment area as it develops plans to meet the ozone standards. The gas plants that operate in PSCo’s non-attainment area mayany associated costs would be required to improve or add controls, implement further work practices and/or implement enhanced emissions monitoring as part of future Colorado state plans.recoverable through regulatory mechanisms.

Legal Contingencies

PSCo is involved in various litigation matters that are being defended and handled in the ordinary course of business. The assessment of whether a loss is probable or is a reasonable possibility, and whether the loss or a range of loss is estimable, often involves a series of complex judgments about future events. Management maintains accruals for such losses that are probable of being incurred and subject to reasonable estimation. Management is sometimes unable to estimate an amount or range of a reasonably possible loss in certain situations, including but not limited to when (1) the damages sought are indeterminate, (2) the proceedings are in the early stages, or (3) the matters involve novel or unsettled legal theories. In such cases, there is considerable uncertainty regarding the timing or ultimate resolution of such matters, including a possible eventual loss. For current proceedings not specifically reported herein, management does not anticipate that the ultimate liabilities, if any, arising from such current proceedings would have a material effect on PSCo’s financial statements. Unless otherwise required by GAAP, legal fees are expensed as incurred.


Employment, Tort and Commercial Litigation

Line Extension Disputes — In December 2015, Development Recovery Company (DRC) filed a lawsuit in the Denver District Court, stating PSCo failed to award proper allowances and refunds for line extensions to new developments pursuant to the terms of electric and gas service agreements entered into by PSCo and various developers. The dispute involved claims by over fifty developers. In February 2018, the Colorado Supreme Court denied DRC’s petition to appeal the Denver District Court’s dismissal of the lawsuit, effectively terminating this litigation. However, in January 2018, DRC filed a new lawsuit in Boulder County District Court, asserting a single claim that PSCo was required to file its line extension agreements with the CPUC but failed to do so. This claim is substantially similar to the arguments previously raised by DRC. PSCo filed a motion to dismiss this claim, which was granted in May 2018. DRC subsequently filed an appeal to the Colorado Court of Appeals. It is uncertain when a decision will be rendered regarding this appeal.
 
PSCo has concluded that a loss is remote with respect to this matter as the service agreements were developed to implement CPUC approved tariffs and PSCo has complied with the tariff provisions. Also, if a loss were sustained, PSCo believes it would be allowed to recover these costs through traditional regulatory mechanisms. The amount or range in dispute is presently unknown and no accrual has been recorded for this matter.


7.Borrowings and Other Financing Instruments

Short-Term Borrowings

Money Pool — Xcel Energy Inc. and its utility subsidiaries have established a money pool arrangement that allows for short-term investments in and borrowings between the utility subsidiaries. Xcel Energy Inc. may make investments in the utility subsidiaries at market-based interest rates; however, the money pool arrangement does not allow the utility subsidiaries to make investments in Xcel Energy Inc. Money pool borrowings for PSCo were as follows:
(Amounts in Millions, Except Interest Rates) Three Months Ended June 30, 2018 Year Ended Dec. 31, 2017 Three Months Ended Sept. 30, 2018 Year Ended Dec. 31, 2017
Borrowing limit $250
 $250
 $250
 $250
Amount outstanding at period end 
 
 
 
Average amount outstanding 60
 
 
 
Maximum amount outstanding 156
 20
 
 20
Weighted average interest rate, computed on a daily basis 1.84% 0.92% N/A
 0.92%
Weighted average interest rate at period end N/A
 N/A
 N/A
 N/A

Commercial Paper — PSCo meets its short-term liquidity requirements primarily through the issuance of commercial paper and borrowings under its credit facility and the money pool. Commercial paper outstanding for PSCo was as follows:
(Amounts in Millions, Except Interest Rates) Three Months Ended June 30, 2018 Year Ended Dec. 31, 2017 Three Months Ended Sept. 30, 2018 Year Ended Dec. 31, 2017
Borrowing limit $700
 $700
 $700
 $700
Amount outstanding at period end 
 
 
 
Average amount outstanding 84
 54
 
 54
Maximum amount outstanding 257
 268
 
 268
Weighted average interest rate, computed on a daily basis 2.17% 1.08% N/A
 1.08%
Weighted average interest rate at period end N/A
 N/A
 N/A
 N/A

Letters of Credit PSCo uses letters of credit, generally with terms of one year, to provide financial guarantees for certain operating obligations. At JuneSept. 30, 2018 and Dec. 31, 2017, there were $4$10 million and $3 million, respectively, of letters of credit outstanding under the credit facility. The contract amounts of these letters of credit approximate their fair value and are subject to fees.

Credit Facility — In order to use its commercial paper program to fulfill short-term funding needs, PSCo must have a revolving credit facility in place at least equal to the amount of its commercial paper borrowing limit and cannot issue commercial paper in an aggregate amount exceeding available capacity under this credit facility. The credit facility provides short-term financing in the form of notes payable to banks, letters of credit and back-up support for commercial paper borrowings.


At JuneSept. 30, 2018, PSCo had the following committed credit facility available (in millions of dollars):
Credit Facility (a)
Credit Facility (a)
 
Drawn (b)
 Available
Credit Facility (a)
 
Drawn (b)
 Available
$700
 $4
 $696
700
 $10
 $690

(a)    This credit facility expires in June 2021.
(b)    Includes outstanding commercial paper and letters of credit.

All credit facility bank borrowings, outstanding letters of credit and outstanding commercial paper reduce the available capacity under the credit facility. PSCo had no direct advances on the credit facility outstanding at JuneSept. 30, 2018 and Dec. 31, 2017.

Long-Term Borrowings

PSCo issued $350 million of 3.70 percent first mortgage green bonds due June 15, 2028 and $350 million of 4.10 percent first mortgage green bonds due June 15, 2048.


8.Fair Value of Financial Assets and Liabilities

Fair Value Measurements

The accounting guidance for fair value measurements and disclosures provides a single definition of fair value and requires certain disclosures about assets and liabilities measured at fair value. A hierarchical framework for disclosing the observability of the inputs utilized in measuring assets and liabilities at fair value is established by this guidance. The three levels in the hierarchy are as follows:

Level 1 Quoted prices are available in active markets for identical assets or liabilities as of the reporting date. The types of assets and liabilities included in Level 1 are highly liquid and actively traded instruments with quoted prices.

Level 2 Pricing inputs are other than quoted prices in active markets, but are either directly or indirectly observable as of the reporting date. The types of assets and liabilities included in Level 2 are typically either comparable to actively traded securities or contracts, or priced with models using highly observable inputs.

Level 3 Significant inputs to pricing have little or no observability as of the reporting date. The types of assets and liabilities included in Level 3 are those valued with models requiring significant management judgment or estimation.

Specific valuation methods include the following:

Cash equivalents — The fair values of cash equivalents are generally based on cost plus accrued interest; money market funds are measured using quoted net asset value.

Interest rate derivatives — The fair values of interest rate derivatives are based on broker quotes that utilize current market interest rate forecasts.

Commodity derivatives — The methods used to measure the fair value of commodity derivative forwards and options utilize forward prices and volatilities, as well as pricing adjustments for specific delivery locations, and are generally assigned a Level 2 classification. When contractual settlements extend to periods beyond those readily observable on active exchanges or quoted by brokers, the significance of the use of less observable forecasts of long-term forward prices and volatilities on a valuation is evaluated, and may result in Level 3 classification.

Derivative Instruments Fair Value Measurements

PSCo enters into derivative instruments, including forward contracts, futures, swaps and options, for trading purposes and to manage risk in connection with changes in interest rates, utility commodity prices and vehicle fuel prices.

Interest Rate Derivatives — PSCo enters into various instruments that effectively fix the interest payments on certain floating rate debt obligations or effectively fix the yield or price on a specified benchmark interest rate for an anticipated debt issuance for a specific period. These derivative instruments are generally designated as cash flow hedges for accounting purposes.

At JuneSept. 30, 2018, accumulated other comprehensive losses related to interest rate derivatives included $1.2 million of net losses expected to be reclassified into earnings during the next 12 months as the related hedged interest rate transactions impact earnings, including forecasted amounts for unsettled hedges, as applicable.


Wholesale and Commodity Trading Risk — PSCo conducts various wholesale and commodity trading activities, including the purchase and sale of electric capacity, energy, energy-related instruments and natural gas related instruments, including derivatives. PSCo’s risk management policy allows management to conduct these activities within guidelines and limitations as approved by its risk management committee, which is made up of management personnel not directly involved in the activities governed by this policy.

Commodity Derivatives — PSCo enters into derivative instruments to manage variability of future cash flows from changes in commodity prices in its electric and natural gas operations, as well as for trading purposes. This could include the purchase or sale of energy or energy-related products, natural gas to generate electric energy, natural gas for resale, and vehicle fuel.


PSCo enters into derivative instruments that mitigate commodity price risk on behalf of electric and natural gas customers but may not be designated as qualifying hedging transactions. Changes in the fair value of non-trading commodity derivative instruments are recorded in other comprehensive income or deferred as a regulatory asset or liability. The classification as a regulatory asset or liability is based on commission approved regulatory recovery mechanisms. PSCo had no income related to the ineffectiveness of cash flow hedges for the three and sixnine months ended JuneSept. 30, 2018 and 2017.

Additionally, PSCo enters into commodity derivative instruments for trading purposes not directly related to commodity price risks associated with serving its electric and natural gas customers. Changes in the fair value of these commodity derivatives are recorded in electric operating revenues, net of amounts credited to customers under margin-sharing mechanisms.

The following table details the gross notional amounts of commodity forwards and options at JuneSept. 30, 2018 and Dec. 31, 2017:
(Amounts in Thousands) (a)(b)
 June 30, 2018 Dec. 31, 2017 Sept. 30, 2018 Dec. 31, 2017
Megawatt hours of electricity 20,813
 22,260
 21,474
 22,260
Million British thermal units of natural gas 18,798
 13,410
 30,763
 13,410

(a) 
Amounts are not reflective of net positions in the underlying commodities.
(b) 
Notional amounts for options are included on a gross basis, but are weighted for the probability of exercise.

The following tables detail the impact of derivative activity during the three and nine months ended JuneSept. 30, 2018 and 2017 on accumulated other comprehensive loss, regulatory assets and liabilities, and income:
  Three Months Ended June 30, 2018 
  
Pre-Tax Fair Value
Losses Recognized
During the Period in:
 
Pre-Tax Losses
Reclassified into Income
During the Period from:
   
(Thousands of Dollars) 
Accumulated
Other
Comprehensive
Loss
 
Regulatory
(Assets) and
Liabilities
 
Accumulated
Other
Comprehensive
Loss
 
Regulatory
Assets and
(Liabilities)
 
Pre-Tax Gains
Recognized
During the Period
in Income
 
Derivatives designated as cash flow hedges           
Interest rate $
 $
 $402
(a) 
$
 $
 
Total $
 $
 $402
 $
 $
 
Other derivative instruments           
Commodity trading $
 $
 $
 $
 $200
(b) 
Natural gas commodity 
 (249) 
 
 
(c) 
Total $
 $(249) $
 $
 $200
 
 Six Months Ended June 30, 2018  Three Months Ended Sept. 30, 2018 
 
Pre-Tax Fair Value
Losses Recognized
During the Period in:
 
Pre-Tax Losses
Reclassified into Income
During the Period from:
 
Pre-Tax (Gains) Losses
Recognized
During the Period
in Income
  
Pre-Tax Fair Value
(Losses) Recognized
During the Period in:
 
Pre-Tax Losses
Reclassified into Income
During the Period from:
   
(Thousands of Dollars) 
Accumulated
Other
Comprehensive
Loss
 
Regulatory
(Assets) and
Liabilities
 
Accumulated
Other
Comprehensive
Loss
 
Regulatory
Assets and
(Liabilities)
  
Accumulated
Other
Comprehensive
Loss
 
Regulatory
(Assets) and
Liabilities
 
Accumulated
Other
Comprehensive
Loss
 
Regulatory
Assets and
(Liabilities)
 
Pre-Tax Gains
Recognized
During the Period
in Income
 
Derivatives designated as cash flow hedges                      
Interest rate $
 $
 $800
(a) 
$
 $
  $
 $
 $407
(a) 
$
 $
 
Total $
 $
 $800
 $
 $
  $
 $
 $407
 $
 $
 
Other derivative instruments  
                    
Commodity trading $
 $
 $
 $
 $724
(b) 
 $
 $
 $
 $
 $2,004
(b) 
Natural gas commodity 
 (420) 
 2,749
(c) 
(1,581)
(c) 
 
 (1,187) 
 
(c) 

(c) 
Total $
 $(420) $
 $2,749
 $(857)  $
 $(1,187) $
 $
 $2,004
 

 Three Months Ended June 30, 2017  Nine Months Ended Sept. 30, 2018 
 
Pre-Tax Fair Value
Losses Recognized
During the Period in:
 
Pre-Tax Losses
Reclassified into Income
During the Period from:
    
Pre-Tax Fair Value
(Losses) Recognized
During the Period in:
 
Pre-Tax Losses
Reclassified into Income
During the Period from:
 
Pre-Tax Gains (Losses)
Recognized
During the Period
in Income
 
(Thousands of Dollars) 
Accumulated
Other
Comprehensive
Loss
 
Regulatory
(Assets) and
Liabilities
 
Accumulated
Other
Comprehensive
Loss
 
Regulatory
Assets and
(Liabilities)
 
Pre-Tax Losses
Recognized
During the Period
in Income
  
Accumulated
Other
Comprehensive
Loss
 
Regulatory
(Assets) and
Liabilities
 
Accumulated
Other
Comprehensive
Loss
 
Regulatory
Assets and
(Liabilities)
 
Derivatives designated as cash flow hedges                      
Interest rate $
 $
 $403
(a) 
$
 $
  $
 $
 $1,207
(a) 
$
 $
 
Total $
 $
 $403
 $
 $
  $
 $
 $1,207
 $
 $
 
Other derivative instruments             
         
Commodity trading $
 $
 $
 $
 $(192)
(b) 
 $
 $
 $
 $
 $2,728
(b) 
Natural gas commodity 
 (1,621) 
 
 
(c) 
 
 (1,607) 
 2,749
(c) 
(1,581)
(c) 
Total $
 $(1,621) $
 $
 $(192)  $
 $(1,607) $
 $2,749
 $1,147
 
 Six Months Ended June 30, 2017  Three Months Ended Sept. 30, 2017 
 
Pre-Tax Fair Value
Losses Recognized
During the Period in:
 
Pre-Tax Losses
Reclassified into Income
During the Period from:
    
Pre-Tax Fair Value
(Losses) Recognized
During the Period in:
 
Pre-Tax Losses
Reclassified into Income
During the Period from:
   
(Thousands of Dollars) 
Accumulated
Other
Comprehensive
Loss
 
Regulatory
(Assets) and
Liabilities
 
Accumulated
Other
Comprehensive
Loss
 
Regulatory
Assets and
(Liabilities)
 
Pre-Tax Gains (Losses)
Recognized
During the Period
in Income
  
Accumulated
Other
Comprehensive
Loss
 
Regulatory
(Assets) and
Liabilities
 
Accumulated
Other
Comprehensive
Loss
 
Regulatory
Assets and
(Liabilities)
 
Pre-Tax Losses
Recognized
During the Period
in Income
 
Derivatives designated as cash flow hedges                      
Interest rate $
 $
 $801
(a) 
$
 $
  $
 $
 $407
(a) 
$
 $
 
Total $
 $
 $801
 $
 $
  $
 $
 $407
 $
 $
 
Other derivative instruments                      
Commodity trading $
 $
 $
 $
 $187
(b) 
 $
 $
 $
 $
 $(211)
(b) 
Natural gas commodity 
 (7,008) 
 282
(c) 
(2,990)
(c) 
 
 (1,635) 
 
 
(c) 
Total $
 $(7,008) $
 $282
 $(2,803)  $
 $(1,635) $
 $
 $(211) 

  Nine Months Ended Sept. 30, 2017 
  
Pre-Tax Fair Value
(Losses) Recognized
During the Period in:
 
Pre-Tax Losses
Reclassified into Income
During the Period from:
   
(Thousands of Dollars) 
Accumulated
Other
Comprehensive
Loss
 
Regulatory
(Assets) and
Liabilities
 
Accumulated
Other
Comprehensive
Loss
 
Regulatory
Assets and
(Liabilities)
 
Pre-Tax Losses
Recognized
During the Period
in Income
 
Derivatives designated as cash flow hedges           
Interest rate $
 $
 $1,208
(a) 
$
 $
 
Total $
 $
 $1,208
 $
 $
 
Other derivative instruments           
Commodity trading $
 $
 $
 $
 $(23)
(b) 
Natural gas commodity 
 (8,643) 
 282
(c) 
(2,990)
(c) 
Total $
 $(8,643) $
 $282
 $(3,013) 

(a) 
Amounts are recorded to interest charges.
(b) 
Amounts are recorded to interest charges. Amounts are recorded to electric operating revenues. Portions of these gains and losses are subject to sharing with electric customers through margin-sharing mechanisms and deducted from gross revenue as appropriate.
(c) 
Certain derivatives are utilized to mitigate natural gas price risk for electric generation and are recorded to electric fuel and purchased power, subject to cost-recovery mechanisms and reclassified to a regulatory asset, as appropriate. Amounts for the three and sixnine months ended JuneSept. 30, 2018 included no settlement gains or losses and $1.2 million of settlement losses, respectively. Amounts for the three and sixnine months ended JuneSept. 30, 2017 included no settlement gains or losses and $0.9 million of settlement gains, respectively. The remaining derivative settlement gains and losses for the sixthree and nine months ended JuneSept. 30, 2018 and 2017 relate to natural gas operations and are recorded to cost of natural gas sold and transported. These gains and losses are subject to cost-recovery mechanisms and reclassified out of income to a regulatory asset or liability, as appropriate.

PSCo had no derivative instruments designated as fair value hedges during the three and sixnine months ended JuneSept. 30, 2018 and 2017. Therefore, no gains or losses from fair value hedges or related hedged transactions were recognized for these periods.

Consideration of Credit Risk and Concentrations — PSCo continuously monitors the creditworthiness of the counterparties to its interest rate derivatives and commodity derivative contracts prior to settlement, and assesses each counterparty’s ability to perform on the transactions set forth in the contracts. Given this assessment, as well as an assessment of the impact of PSCo’s own credit risk when determining the fair value of derivative liabilities, the impact of credit risk was immaterial to the fair value of unsettled commodity derivatives presented in the consolidated balance sheets.

PSCo employs additional credit risk control mechanisms when appropriate, such as letters of credit, parental guarantees, standardized master netting agreements and termination provisions that allow for offsetting of positive and negative exposures. Credit exposure is monitored and, when necessary, the activity with a specific counterparty is limited until credit enhancement is provided.


PSCo’s most significant concentrations of credit risk with particular entities or industries are contracts with counterparties to its wholesale, trading and non-trading commodity activities. At JuneSept. 30, 2018, four of PSCo’s 10 most significant counterparties for these activities, comprising $27.6$24.1 million or 4742 percent of this credit exposure, had investment grade credit ratings from Standard & Poor’s, Moody’s or Fitch Ratings. Five of the 10 most significant counterparties, comprising $12.2$16.6 million or 2129 percent of this credit exposure, were not rated by these external agencies, but based on PSCo’s internal analysis, had credit quality consistent with investment grade. The one remaining significant counterparty, comprising $5.2$1.1 million or 92 percent of this credit exposure, had credit quality less than investment grade, based on ratings from external analysis. NineEight of these significant counterparties are municipal or cooperative electric entities, or other utilities.

Credit Related Contingent Features  Contract provisions for derivative instruments that PSCo enters into, including those accounted for as normal purchase-normal sale contracts and therefore not reflected on the balance sheet, may require the posting of collateral or settlement of the contracts for various reasons, including if PSCo’s credit ratings are downgraded below its investment grade credit rating by any of the major credit rating agencies or for cross-default contractual provisions that could result in the settlement of such contracts if there was a failure under other financing arrangements related to payment terms or other covenants. At JuneSept. 30, 2018 and Dec. 31, 2017, there were no derivative instruments in a material liability position with such underlying contract provisions.


Certain derivative instruments are also subject to contract provisions that contain adequate assurance clauses. These provisions allow counterparties to seek performance assurance, including cash collateral, in the event that PSCo’s ability to fulfill its contractual obligations is reasonably expected to be impaired. PSCo had no collateral posted related to adequate assurance clauses in derivative contracts as of JuneSept. 30, 2018 and Dec. 31, 2017.

Recurring Fair Value Measurements  The following table presents, for each of the fair value hierarchy levels, PSCo’s assets and liabilities measured at fair value on a recurring basis at JuneSept. 30, 2018:

 June 30, 2018 Sept. 30, 2018
 Fair Value 
Fair Value
Total
 
Counterparty
Netting (b)
   Fair Value 
Fair Value
Total
 
Counterparty
Netting (b)
  
(Thousands of Dollars) Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total
Current derivative assets                        
Other derivative instruments:                        
Commodity trading $332
 $12,812
 $118
 $13,262
 $(9,729) $3,533
 $695
 $21,035
 $
 $21,730
 $(6,861) $14,869
Natural gas commodity 
 919
 
 919
 
 919
 
 1,233
 
 1,233
 
 1,233
Total current derivative assets $332
 $13,731
 $118
 $14,181
 $(9,729) 4,452
 $695
 $22,268
 $
 $22,963
 $(6,861) 16,102
PPAs (a)
           888
           460
Current derivative instruments           $5,340
           $16,562
Noncurrent derivative assets                        
Other derivative instruments:                        
Commodity trading $1
 $2,715
 $
 $2,716
 $
 $2,716
 $6
 $3,682
 $
 $3,688
 $
 $3,688
Total noncurrent derivative assets $1
 $2,715
 $
 $2,716
 $
 2,716
 $6
 $3,682
 $
 $3,688
 $
 3,688
PPAs (a)
           
           
Noncurrent derivative instruments           $2,716
           $3,688

 June 30, 2018 Sept. 30, 2018
 Fair Value 
Fair Value
Total
 
Counterparty
Netting (b)
   Fair Value 
Fair Value
Total
 
Counterparty
Netting (b)
  
(Thousands of Dollars) Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total
Current derivative liabilities                        
Other derivative instruments:                        
Commodity trading $333
 $12,409
 $
 $12,742
 $(12,474) $268
 $580
 $20,219
 $13
 $20,812
 $(15,853) $4,959
Total current derivative liabilities $333
 $12,409
 $
 $12,742
 $(12,474) 268
 $580
 $20,219
 $13
 $20,812
 $(15,853) 4,959
PPAs (a)
           5,160
           3,959
Current derivative instruments           $5,428
           $8,918
Noncurrent derivative liabilities                        
Other derivative instruments:                        
Commodity trading $
 $2,382
 $
 $2,382
 $
 $2,382
 $
 $3,156
 $
 $3,156
 $
 $3,156
Total noncurrent derivative liabilities $
 $2,382
 $
 $2,382
 $
 2,382
 $
 $3,156
 $
 $3,156
 $
 3,156
PPAs (a)
           89
           
Noncurrent derivative instruments           $2,471
           $3,156

(a) 
During 2006, PSCo qualified these contracts under the normal purchase exception. Based on this qualification, the contracts are no longer adjusted to fair value and the previous carrying value of these contracts is being amortized over the remaining contract lives along with the offsetting regulatory assets and liabilities.
(b) 
PSCo nets derivative instruments and related collateral in its consolidated balance sheet when supported by a legally enforceable master netting agreement, and all derivative instruments and related collateral amounts were subject to master netting agreements at JuneSept. 30, 2018. At JuneSept. 30, 2018, derivative assets and liabilities include no obligations to return cash collateral and rights to reclaim cash collateral of $2.7$9.0 million. The counterparty netting amounts presented exclude settlement receivables and payables and non-derivative amounts that may be subject to the same master netting agreements.


The following table presents, for each of the fair value hierarchy levels, PSCo’s assets and liabilities measured at fair value on a recurring basis at Dec. 31, 2017:
  Dec. 31, 2017
  Fair Value 
Fair Value
Total
 
Counterparty
Netting (b)
  
(Thousands of Dollars) Level 1 Level 2 Level 3   Total
Current derivative assets            
Other derivative instruments:            
Commodity trading $528
 $4,488
 $12
 $5,028
 $(3,554) $1,474
Natural gas commodity 
 18
 
 18
 (10) 8
Total current derivative assets $528
 $4,506
 $12
 $5,046
 $(3,564) 1,482
PPAs (a)
           1,715
Current derivative instruments           $3,197
Noncurrent derivative assets            
Other derivative instruments:    
    
  
  
Commodity trading $
 $1,541
 $
 $1,541
 $(563) $978
Total noncurrent derivative assets $
 $1,541
 $
 $1,541
 $(563) 978
PPAs (a)
           31
Noncurrent derivative instruments           $1,009



  Dec. 31, 2017
  Fair Value 
Fair Value
Total
 
Counterparty
Netting (b)
  
(Thousands of Dollars) Level 1 Level 2 Level 3   Total
Current derivative liabilities            
Other derivative instruments:            
Commodity trading $446
 $4,285
 $6
 $4,737
 $(3,431) $1,306
Natural gas commodity 
 1,016
 
 1,016
 (10) 1,006
Total current derivative liabilities $446
 $5,301
 $6
 $5,753
 $(3,441) 2,312
PPAs (a)
           5,036
Current derivative instruments           $7,348
Noncurrent derivative liabilities            
Commodity trading $
 $1,362
 $
 $1,362
 $(563) $799
Total noncurrent derivative liabilities $
 $1,362
 $
 $1,362
 $(563) 799
PPAs (a)
           $2,669
Noncurrent derivative instruments           $3,468

(a) 
During 2006, PSCo qualified these contracts under the normal purchase exception. Based on this qualification, the contracts are no longer adjusted to fair value and the previous carrying value of these contracts is being amortized over the remaining contract lives along with the offsetting regulatory assets and liabilities.
(b) 
PSCo nets derivative instruments and related collateral in its consolidated balance sheet when supported by a legally enforceable master netting agreement, and all derivative instruments and related collateral amounts were subject to master netting agreements at Dec. 31, 2017. At Dec. 31, 2017, derivative assets and liabilities include no obligations to return cash collateral or rights to reclaim cash collateral. The counterparty netting amounts presented exclude settlement receivables and payables and non-derivative amounts that may be subject to the same master netting agreements.

There were $0.1 million of gains recognized in earnings for Level 3 commodity trading derivatives in the three and six months ended June 30, 2018. There were immaterial gains and losses recognized in earnings for Level 3 commodity trading derivatives in the three and sixnine months ended JuneSept. 30, 2018 and 2017.

PSCo recognizes transfers between levels as of the beginning of each period. There were no transfers of amounts between levels for derivative instruments for the three and sixnine months ended JuneSept. 30, 2018 and 2017.


Fair Value of Long-Term Debt

As of JuneSept. 30, 2018 and Dec. 31, 2017, other financial instruments for which the carrying amount did not equal fair value were as follows:
 June 30, 2018 Dec. 31, 2017 Sept. 30, 2018 Dec. 31, 2017
(Thousands of Dollars) 
Carrying
Amount
 Fair Value 
Carrying
Amount
 Fair Value 
Carrying
Amount
 Fair Value 
Carrying
Amount
 Fair Value
Long-term debt, including current portion $5,300,062
 $5,464,543
 $4,608,275
 $5,024,840
 $4,998,403
 $5,090,696
 $4,608,275
 $5,024,840

The fair value of PSCo’s long-term debt is estimated based on recent trades and observable spreads from benchmark interest rates for similar securities. The fair value estimates are based on information available to management as of JuneSept. 30, 2018 and Dec. 31, 2017, and given the observability of the inputs to these estimates, the fair values presented for long-term debt have been assigned a Level 2.

9.Other Income, Net

Other income, net consisted of the following:
 Three Months Ended June 30 Six Months Ended June 30 Three Months Ended Sept. 30 Nine Months Ended Sept. 30
(Thousands of Dollars) 2018 2017 2018 2017 2018 2017 2018 2017
Interest income $508
 $609
 $372
 $984
 $1,366
 $1,422
 $1,738
 $2,406
Other nonoperating income 483
 1,326
 956
 4,747
 1,098
 193
 2,051
 4,940
Other nonoperating expense (3) 
 
 
Insurance policy expense (73) (103) (150) (182) (74) (79) (224) (261)
Benefits non-service cost (119) (513) (148) (1,026) (988) (513) (1,136) (1,539)
Other income, net $799
 $1,319
 $1,030
 $4,523
 $1,399
 $1,023
 $2,429
 $5,546


10.Segment Information

Operating results from the regulated electric utility and regulated natural gas utility are each separately and regularly reviewed by PSCo’s chief operating decision maker. PSCo evaluates performance based on profit or loss generated from the product or service provided. These segments are managed separately because the revenue streams are dependent upon regulated rate recovery, which is separately determined for each segment.

PSCo has the following reportable segments: regulated electric utility, regulated natural gas utility and all other.

PSCo’s regulated electric utility segment generates, transmits and distributes electricity primarily in portions of Colorado. In addition, this segment includes sales for resale and provides wholesale transmission service to various entities in the United States. Regulated electric utility also includes PSCo’s commodity trading operations.
PSCo’s regulated natural gas utility segment transports, stores and distributes natural gas primarily in portions of Colorado.
Revenues from operating segments not included above are below the necessary quantitative thresholds and are therefore included in the all other category. Those primarily include steam revenue, appliance repair services and nonutility real estate activities.

Asset and capital expenditure information is not provided for PSCo’s reportable segments because as an integrated electric and natural gas utility, PSCo operates significant assets that are not dedicated to a specific business segment, and reporting assets and capital expenditures by business segment would require arbitrary and potentially misleading allocations which may not necessarily reflect the assets that would be required for the operation of the business segments on a stand-alone basis.

To report income from operations for regulated electric and regulated natural gas utility segments, the majority of costs are directly assigned to each segment. However, some costs, such as common depreciation, common operating and maintenance (O&M) expenses and interest expense are allocated based on cost causation allocators. A general allocator is used for certain general and administrative expenses, including office supplies, rent, property insurance and general advertising.
(Thousands of Dollars) Regulated Electric Regulated Natural Gas All Other Reconciling Eliminations Consolidated Total
Three Months Ended June 30, 2018          
Operating revenues (a)(b)
 $716,195
 $186,661
 $9,010
 $
 $911,866
Intersegment revenues 76
 79
 
 (155) 
Total revenues $716,271
 $186,740
 $9,010
 $(155) $911,866
Net income (loss) $101,956
 $20,963
 $(623) $
 $122,296

(Thousands of Dollars) Regulated Electric Regulated Natural Gas All Other Reconciling Eliminations Consolidated Total Regulated Electric Regulated Natural Gas All Other Reconciling Eliminations Consolidated Total
Three Months Ended June 30, 2017          
Three Months Ended Sept. 30, 2018          
Operating revenues (a)(b)
 $729,920
 $192,777
 $8,219
 $
 $930,916
 $894,786
 $157,205
 $8,688
 $
 $1,060,679
Intersegment revenues 67
 40
 
 (107) 
 32
 292
 
 (324) 
Total revenues $729,987
 $192,817
 $8,219
 $(107) $930,916
 $894,818
 $157,497
 $8,688
 $(324) $1,060,679
Net income $87,403
 $12,835
 $349
 $
 $100,587
 $191,742
 $15,070
 $300
 $
 $207,112
(Thousands of Dollars) Regulated Electric Regulated Natural Gas All Other Reconciling Eliminations Consolidated Total
Three Months Ended Sept. 30, 2017          
Operating revenues (a)(b)
 $877,604
 $142,389
 $10,300
 $
 $1,030,293
Intersegment revenues 47
 222
 
 (269) 
Total revenues $877,651
 $142,611
 $10,300
 $(269) $1,030,293
Net income $178,648
 $5,815
 $1,614
 $
 $186,077
(a)    Operating revenues include $0 millionan immaterial amount of affiliate electric revenue for the three months ended JuneSept. 30, 2018 and 2017.
(b)    Operating revenues include $1 million of other affiliate revenue for the three months ended JuneSept. 30, 2018 and 2017.
(Thousands of Dollars) Regulated
Electric
 Regulated
Natural Gas
 All
Other
 Reconciling
Eliminations
 Consolidated
Total
 Regulated
Electric
 Regulated
Natural Gas
 All
Other
 Reconciling
Eliminations
 Consolidated
Total
Six Months Ended June 30, 2018          
Operating revenues from external customers $1,414,469
 $550,647
 $20,048
 $
 $1,985,164
Nine Months Ended Sept. 30, 2018          
Operating revenues (a)(b) $2,309,255
 $707,852
 $28,736
 $
 $3,045,843
Intersegment revenues 188
 143
 
 (331) 
 220
 435
 
 (655) 
Total revenues $1,414,657
 $550,790
 $20,048
 $(331) $1,985,164
 $2,309,475
 $708,287
 $28,736
 $(655) $3,045,843
Net income (loss) $181,507
 $74,675
 $(164) $
 $256,018
Net income $373,249
 $89,745
 $135
 $
 $463,129
(Thousands of Dollars) Regulated
Electric
 Regulated
Natural Gas
 All
Other
 Reconciling
Eliminations
 Consolidated
Total
 Regulated
Electric
 Regulated
Natural Gas
 All
Other
 Reconciling
Eliminations
 Consolidated
Total
Six Months Ended June 30, 2017    
      
Operating revenues from external customers $1,441,308
 $548,913
 $21,229
 $
 $2,011,450
Nine Months Ended Sept. 30, 2017    
      
Operating revenues (a)(b) $2,318,912
 $691,302
 $31,529
 $
 $3,041,743
Intersegment revenues 159
 96
 
 (255) 
 206
 318
 
 (524) 
Total revenues $1,441,467
 $549,009
 $21,229
 $(255) $2,011,450
 $2,319,118
 $691,620
 $31,529
 $(524) $3,041,743
Net income $163,547
 $47,318
 $1,268
 $
 $212,133
 $342,195
 $53,133
 $2,882
 $
 $398,210
(a)    Operating revenues include $0 millionan immaterial amount and $1 million of affiliate electric revenue for the sixnine months ended JuneSept. 30, 2018 and 2017.
(b)    Operating revenues include $2$3 million of other affiliate revenue for the sixnine months ended JuneSept. 30, 2018 and 2017.

11.Benefit Plans and Other Postretirement Benefits

Components of Net Periodic Benefit Cost (Credit)
 Three Months Ended June 30 Three Months Ended Sept. 30
 2018 2017 2018 2017 2018 2017 2018 2017
(Thousands of Dollars) Pension Benefits 
Postretirement Health
Care Benefits
 Pension Benefits 
Postretirement Health
Care Benefits
Service cost $7,271
 $6,820
 $152
 $192
 $7,272
 $6,820
 $153
 $192
Interest cost (a)
 11,814
 12,640
 3,748
 4,191
 11,813
 12,639
 3,748
 4,191
Expected return on plan assets (a)
 (17,130) (17,134) (5,674) (5,476) (17,130) (17,134) (5,675) (5,476)
Amortization of prior service credit (a)
 (845) (803) (1,544) (1,562) (844) (803) (1,545) (1,562)
Amortization of net loss (a)
 7,815
 7,089
 1,021
 961
 7,814
 7,089
 1,021
 961
Net periodic benefit cost (credit) 8,925
 8,612
 (2,297) (1,694) 8,925
 8,611
 (2,298) (1,694)
Credits not recognized due to the effects of regulation 895
 426
 
 
(Costs) credits not recognized due to the effects of regulation (4,088) 736
 1,426
 
Net benefit cost (credit) recognized for financial reporting $9,820
 $9,038
 $(2,297) $(1,694) $4,837
 $9,347
 $(872) $(1,694)


 Six Months Ended June 30 Nine Months Ended Sept. 30
 2018 2017 2018 2017 2018 2017 2018 2017
(Thousands of Dollars) Pension Benefits Postretirement Health
Care Benefits
 Pension Benefits Postretirement Health
Care Benefits
Service cost $14,542
 $13,640
 $304
 $384
 $21,814
 $20,460
 $457
 $576
Interest cost (a)
 23,628
 25,280
 7,497
 8,382
 35,441
 37,919
 11,245
 12,573
Expected return on plan assets (a)
 (34,260) (34,268) (11,349) (10,952) (51,390) (51,402) (17,024) (16,428)
Amortization of prior service credit (a)
 (1,690) (1,606) (3,089) (3,124) (2,534) (2,409) (4,634) (4,686)
Amortization of net loss (a)
 15,630
 14,178
 2,042
 1,922
 23,444
 21,267
 3,063
 2,883
Net periodic benefit cost (credit) 17,850
 17,224
 (4,595) (3,388) 26,775
 25,835
 (6,893) (5,082)
Credits not recognized due to the effects of regulation 2,370
 1,162
 
 
(Costs) credits not recognized due to the effects of regulation (1,718) 1,898
 1,426
 
Net benefit cost (credit) recognized for financial reporting $20,220
 $18,386
 $(4,595) $(3,388) $25,057
 $27,733
 $(5,467) $(5,082)

(a)  
The components of net periodic cost other than the service cost component are included in the line item “other income, net” in the income statement or capitalized on the balance sheet as a regulatory asset.

In January 2018, contributions of $150 million were made across four of Xcel Energy’s pension plans, of which $22.0 million was attributable to PSCo. Xcel Energy does not expect additional pension contributions during 2018.


12.Other Comprehensive Income (Loss)

Changes in accumulated other comprehensive loss, net of tax, for the three and sixnine months ended JuneSept. 30, 2018 and 2017 were as follows:
 Three Months Ended June 30, 2018 Three Months Ended Sept. 30, 2018
(Thousands of Dollars) Gains and Losses on Cash Flow Hedges Defined Benefit and Postretirement Items Total Gains and Losses on Cash Flow Hedges Defined Benefit and Postretirement Items Total
Accumulated other comprehensive loss at April 1 $(26,165) $(265) $(26,430)
Accumulated other comprehensive loss at July 1 $(25,862) $(263) $(26,125)
Other comprehensive loss before reclassifications 
 (153) (153)
Losses reclassified from net accumulated other comprehensive loss 303
 2
 305
 310
 155
 465
Net current period other comprehensive income 303
 2
 305
 310
 2
 312
Accumulated other comprehensive loss at June 30 $(25,862) $(263) $(26,125)
Accumulated other comprehensive loss at Sept. 30 $(25,552) $(261) $(25,813)
 Three Months Ended June 30, 2017 Three Months Ended Sept. 30, 2017
(Thousands of Dollars) Gains and Losses on Cash Flow Hedges Defined Benefit and Postretirement Items Total Gains and Losses on Cash Flow Hedges Defined Benefit and Postretirement Items Total
Accumulated other comprehensive loss at April 1 $(22,534) $(219) $(22,753)
Accumulated other comprehensive loss at July 1 $(22,284) $(218) $(22,502)
Losses reclassified from net accumulated other comprehensive loss 250
 1
 251
 257
 1
 258
Net current period other comprehensive income 250
 1
 251
 257
 1
 258
Accumulated other comprehensive loss at June 30 $(22,284) $(218) $(22,502)
Accumulated other comprehensive loss at Sept. 30 $(22,027) $(217) $(22,244)
 Six Months Ended June 30, 2018 Nine Months Ended Sept. 30, 2018
(Thousands of Dollars) Gains and Losses on Cash Flow Hedges Defined Benefit and Postretirement Items Total Gains and Losses on Cash Flow Hedges Defined Benefit and Postretirement Items Total
Accumulated other comprehensive loss at Jan. 1 $(26,465) $(267) $(26,732) $(26,465) $(267) $(26,732)
Other comprehensive loss before reclassifications 
 (153) (153)
Losses reclassified from net accumulated other comprehensive loss 603
 4
 607
 913
 159
 1,072
Net current period other comprehensive income 603
 4
 607
 913
 6
 919
Accumulated other comprehensive loss at June 30 $(25,862) $(263) $(26,125)
Accumulated other comprehensive loss at Sept. 30 $(25,552) $(261) $(25,813)

 Six Months Ended June 30, 2017 Nine Months Ended Sept. 30, 2017
(Thousands of Dollars) Gains and Losses on Cash Flow Hedges Defined Benefit and Postretirement Items Total Gains and Losses on Cash Flow Hedges Defined Benefit and Postretirement Items Total
Accumulated other comprehensive loss at Jan. 1 $(22,780) $(220) $(23,000) $(22,780) $(220) $(23,000)
Losses reclassified from net accumulated other comprehensive loss 496
 2
 498
 753
 3
 756
Net current period other comprehensive income 496
 2
 498
 753
 3
 756
Accumulated other comprehensive loss at June 30 $(22,284) $(218) $(22,502)
Accumulated other comprehensive loss at Sept. 30 $(22,027) $(217) $(22,244)

Reclassifications from accumulated other comprehensive loss for the three and sixnine months ended JuneSept. 30, 2018 and 2017 were as follows:
     
 Amounts Reclassified from Accumulated Other
Comprehensive Loss
  Amounts Reclassified from Accumulated Other
Comprehensive Loss
 
(Thousands of Dollars) Three Months Ended June 30, 2018 Three Months Ended June 30, 2017  Three Months Ended Sept. 30, 2018 Three Months Ended Sept. 30, 2017 
Losses on cash flow hedges:  
     
   
Interest rate derivatives $402
(a) 
$403
(a) 
 $407
(a) 
$407
(a) 
Total, pre-tax 402
 403
  407
 407
 
Tax benefit (99) (153)  (97) (150) 
Total, net of tax 303
 250
  310
 257
 
Defined benefit pension and postretirement losses:          
Amortization of net loss 2
(b) 
2
(b) 
 206
(b) 
2
(b) 
Total, pre-tax 2
 2
  206
 2
 
Tax benefit 
 (1)  (51) (1) 
Total, net of tax 2
 1
  155
 1
 
Total amounts reclassified, net of tax $305
 $251
  $465
 $258
 
     
 
Amounts Reclassified from Accumulated
Other Comprehensive Loss
  
Amounts Reclassified from Accumulated
Other Comprehensive Loss
 
(Thousands of Dollars) Six Months Ended June 30, 2018 Six Months Ended June 30, 2017  Nine Months Ended Sept. 30, 2018 Nine Months Ended Sept. 30, 2017 
Losses on cash flow hedges:          
Interest rate derivatives $800
(a) 
$801
(a) 
 $1,207
(a) 
$1,208
(a) 
Total, pre-tax 800
 801
  1,207
 1,208
 
Tax benefit (197) (305)  (294) (455) 
Total, net of tax $603
 $496
  $913
 $753
 
Defined benefit pension and postretirement losses:          
Amortization of net loss $4
(b) 
$4
(b) 
 $210
(b) 
$6
(b) 
Total, pre-tax 4
 4
  210
 6
 
Tax benefit 
 (2)  (51) (3) 
Total, net of tax 4
 2
  159
 3
 
Total amounts reclassified, net of tax $607
 $498
  $1,072
 $756
 
(a) 
Included in interest charges.
(b) 
Included in the computation of net periodic pension and postretirement benefit costs. See Note 11 to the consolidated financial statements for details regarding these benefit plans.

13.Revenues

PSCo principally generates revenue from the generation, transmission, distribution and sale of electricity and the transportation, distribution and sale of natural gas to wholesale and retail customers. Performance obligations related to the sale of energy are satisfied as energy is delivered to customers. PSCo recognizes revenue in an amount that corresponds directly to the price of the energy delivered to the customer. The measurement of energy sales to customers is generally based on the reading of their meters, which occurs on a systematic basis throughout the month. At the end of each month, amounts of energy delivered to customers since the date of the last meter reading are estimated, and the corresponding unbilled revenue is recognized. Contract terms are generally short-term in nature, and as such PSCo does not recognize a separate financing component of its collections from customers. PSCo presents its revenues net of any excise or other fiduciary-type taxes or fees.

PSCo has various rate-adjustment mechanisms in place that provide for the recovery of natural gas, electric fuel and purchased energy costs. These cost-adjustment tariffs may increase or decrease the level of revenue collected from customers and are revised periodically for differences between the total amount collected under the clauses and the costs incurred. When applicable, under governing regulatory commission rate orders, fuel cost over-recoveries (the excess of fuel revenue billed to customers over fuel costs incurred) are deferred as regulatory liabilities and under-recoveries (the excess of fuel costs incurred over fuel revenues billed to customers) are deferred as regulatory assets.


Certain rate rider mechanisms qualify as alternative revenue programs under GAAP. These mechanisms arise from costs imposed upon the utility by action of a regulator or legislative body related to an environmental, public safety or other mandate. When certain criteria are met (including collection within 24 months), revenue is recognized equal to the revenue requirement, which may include return on rate base items and incentives. The mechanisms are revised periodically for differences between the total amount collected and the revenue recognized, which may increase or decrease the level of revenue collected from customers. Alternative revenue is recorded on a gross basis and is disclosed separate from revenue from contracts with customers in the period earned.

In the following tables, revenue is classified by the type of goods/services rendered and market/customer type. The tables also reconcile revenue to the reportable segments.
 Three Months Ended June 30, 2018 Three Months Ended Sept. 30, 2018
(Thousands of Dollars) Electric Natural Gas All Other Total Electric Natural Gas All Other Total
Major revenue types                
Revenue from contracts with customers:                
Residential $222,687
 $104,000
 $2,560
 $329,247
 $315,726
 $84,411
 $2,668
 $402,805
Commercial and industrial (C&I) 383,707
 38,904
 5,326
 427,937
 458,448
 29,111
 4,897
 492,456
Other 11,455
 
 
 11,455
 11,822
 
 
 11,822
Total retail 617,849
 142,904
 7,886
 768,639
 785,996
 113,522
 7,565
 907,083
Wholesale 36,148
 
 
 36,148
 41,200
 
 
 41,200
Transmission 13,159
 
 
 13,159
 16,298
 
 
 16,298
Other 14,696
 18,845
 
 33,541
 10,593
 18,332
 
 28,925
Total revenue from contracts with customers 681,852
 161,749
 7,886
 851,487
 854,087
 131,854
 7,565
 993,506
Alternative revenue and other 34,343
 24,912
 1,124
 60,379
 40,699
 25,351
 1,123
 67,173
Total revenues $716,195
 $186,661
 $9,010
 $911,866
 $894,786
 $157,205
 $8,688
 $1,060,679

  Three Months Ended June 30, 2017
(Thousands of Dollars) Electric Natural Gas All Other Total
Major revenue types        
Revenue from contracts with customers:        
Residential $225,921
 $117,393
 $2,639
 $345,953
C&I 392,280
 45,032
 4,457
 441,769
Other 11,711
 
 
 11,711
Total retail 629,912
 162,425
 7,096
 799,433
Wholesale 41,579
 
 
 41,579
Transmission 13,180
 
 
 13,180
Other 16,837
 20,040
 
 36,877
Total revenue from contracts with customers 701,508
 182,465
 7,096
 891,069
Alternative revenue and other 28,412
 10,312
 1,123
 39,847
Total revenues $729,920
 $192,777
 $8,219
 $930,916
 Six Months Ended June 30, 2018 Three Months Ended Sept. 30, 2017
(Thousands of Dollars) Electric Natural Gas All Other Total Electric Natural Gas All Other Total
Major revenue types                
Revenue from contracts with customers:                
Residential $450,336
 $331,746
 $5,256
 $787,338
 $302,371
 $83,000
 $3,184
 $388,555
C&I 726,933
 124,932
 12,485
 864,350
 457,285
 30,651
 5,993
 493,929
Other 23,631
 
 60
 23,691
 12,237
 
 
 12,237
Total retail 1,200,900
 456,678
 17,801
 1,675,379
 771,893
 113,651
 9,177
 894,721
Wholesale 84,038
 
 
 84,038
 40,443
 
 
 40,443
Transmission 25,411
 
 
 25,411
 14,541
 
 
 14,541
Other 33,527
 43,774
 
 77,301
 17,616
 17,564
 
 35,180
Total revenue from contracts with customers 1,343,876
 500,452
 17,801
 1,862,129
 844,493
 131,215
 9,177
 984,885
Alternative revenue and other 70,593
 50,195
 2,247
 123,035
 33,111
 11,174
 1,123
 45,408
Total revenues $1,414,469
 $550,647
 $20,048
 $1,985,164
 $877,604
 $142,389
 $10,300
 $1,030,293

 Six Months Ended June 30, 2017 Nine Months Ended Sept. 30, 2018
(Thousands of Dollars) Electric Natural Gas All Other Total Electric Natural Gas All Other Total
Major revenue types                
Revenue from contracts with customers:                
Residential $460,355
 $343,303
 $5,203
 $808,861
 $766,062
 $416,157
 $7,924
 $1,190,143
C&I 751,977
 131,274
 13,717
 896,968
 1,185,381
 154,043
 17,382
 1,356,806
Other 24,386
 
 63
 24,449
 35,453
 
 60
 35,513
Total retail 1,236,718
 474,577
 18,983
 1,730,278
 1,986,896
 570,200
 25,366
 2,582,462
Wholesale 85,155
 
 
 85,155
 125,238
 
 
 125,238
Transmission 27,819
 
 
 27,819
 41,709
 
 
 41,709
Other 33,532
 42,650
 
 76,182
 44,120
 62,106
 
 106,226
Total revenue from contracts with customers 1,383,224
 517,227
 18,983
 1,919,434
 2,197,963
 632,306
 25,366
 2,855,635
Alternative revenue and other 58,084
 31,686
 2,246
 92,016
 111,292
 75,546
 3,370
 190,208
Total revenues $1,441,308
 $548,913
 $21,229
 $2,011,450
 $2,309,255
 $707,852
 $28,736
 $3,045,843

  Nine Months Ended Sept. 30, 2017
(Thousands of Dollars) Electric Natural Gas All Other Total
Major revenue types        
Revenue from contracts with customers:        
Residential $762,726
 $426,303
 $8,387
 $1,197,416
C&I 1,209,262
 161,925
 19,710
 1,390,897
Other 36,623
 
 63
 36,686
Total retail 2,008,611
 588,228
 28,160
 2,624,999
Wholesale 125,598
 
 
 125,598
Transmission 42,360
 
 
 42,360
Other 51,148
 60,214
 
 111,362
Total revenue from contracts with customers 2,227,717
 648,442
 28,160
 2,904,319
Alternative revenue and other 91,195
 42,860
 3,369
 137,424
Total revenues $2,318,912
 $691,302
 $31,529
 $3,041,743

Item 2 — MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS

Discussion of financial condition and liquidity for PSCo is omitted per conditions set forth in general instructions H (1) (a) and (b) of Form 10-Q for wholly owned subsidiaries. It is replaced with management’s narrative analysis of the results of operations set forth in general instructions H (2) (a) of Form 10-Q for wholly owned subsidiaries (reduced disclosure format).

Financial Review

The following discussion and analysis by management focuses on those factors that had a material effect on PSCo’s financial condition, results of operations and cash flows during the periods presented, or are expected to have a material impact in the future. It should be read in conjunction with the accompanying unaudited consolidated financial statements and related notes to the consolidated financial statements. Due to the seasonality of PSCo’s electric and natural gas sales, such interim results are not necessarily an appropriate base from which to project annual results.


Forward-Looking Statements

Except for the historical statements contained in this report, the matters discussed herein, are forward-looking statements that are subject to certain risks, uncertainties and assumptions. Such forward-looking statements including the TCJA’s impact to PSCo and its customers, as well as assumptions and other statements are intended to be identified in this document by the words “anticipate,” “believe,” “could,” “estimate,” “expect,” “intend,” “may,” “objective,” “outlook,” “plan,” “project,” “possible,” “potential,” “should,” “will,” “would” and similar expressions. Actual results may vary materially. Forward-looking statements speak only as of the date they are made, and we expressly disclaim any obligation to update any forward-looking information. The following factors, in addition to those discussed elsewhere in this Quarterly Report on Form 10-Q and in other securities filings (including PSCo’s Annual Report on Form 10-K for the fiscal year ended Dec. 31, 2017 and subsequent securities filings), could cause actual results to differ materially from management expectations as suggested by such forward-looking information: changes in environmental laws and regulations; unusual weather and climate change, including compliance with any accompanying legislative and regulatory changes; ability to recover costs from customers; actions of credit rating agencies; general economic conditions, including inflation rates, monetary fluctuations and their impact on capital expenditures and the ability of PSCo and its subsidiaries to obtain financing on favorable terms; business conditions in theavailability or cost of capital; our customers’ and counterparties’ ability to pay their debts to us; assumptions and costs relating to funding our employee benefit plans and health care benefits;; tax laws; operational safety; successful long-term operational planning; commodity risks associated with energy industry; including the riskmarkets and production; costs of a slow down in the U.S. economy or delay in growth, recovery, trade, fiscal, taxation and environmental policies in areas where PSCo has a financial interest; customer business conditions; actions of credit rating agencies; competitive factors including the extent and timing of the entry of additional competition in the markets served by PSCo and its subsidiaries; unusual weather;potential regulatory penalties; effects of geopolitical events, including war and acts of terrorism; cyber security threats and data security breaches; state, federal and foreign legislative and regulatory initiatives that affect cost and investment recovery, have an impact on rates or have an impact on asset operation or ownership or impose environmental compliance conditions; structures that affect the speed and degree to which competition enters the electric and natural gas markets; costs and other effects of legal and administrative proceedings, settlements, investigations and claims; financial or regulatory accounting policies imposed by regulatory bodies; outcomes of regulatory proceedings; availability or cost of capital;fuel costs; and employee work force factors.

Non-GAAP Financial Measures

The following discussion includes financial information prepared in accordance with GAAP, as well as certain non-GAAP financial measures such as electric margin and natural gas margin.  Generally, a non-GAAP financial measure is a numerical measure of a company’s financial performance, financial position or cash flows that excludes (or includes) amounts that are adjusted from the most directly comparable measure calculated and presented in accordance with GAAP. PSCo’s management uses non-GAAP measures internally for financial planning and analysis, for reporting of results to the Board of Directors and when communicating its earnings outlook to analysts and investors. Non-GAAP financial measures are intended to supplement investors’ understanding of our operating performance and should not be considered alternatives for financial measures presented in accordance with GAAP. These measures are discussed in more detail below and may not be comparable to other companies’ similarly titled non-GAAP financial measures.

Electric and Natural Gas Margins

Electric margin is presented as electric revenues less electric fuel and purchased power expenses and natural gas margin is presented as natural gas revenues less the cost of natural gas sold and transported. Expenses incurred for electric fuel and purchased power and the cost of natural gas sold and transported are generally recovered through various recovery mechanisms, and as a result, changes in these expenses are offset in operating revenues. Management believes electric and natural gas margins provide the most meaningful basis for evaluating our operations because they exclude the revenue impact of fluctuations in these expenses.

These margins can be reconciled to operating income, a GAAP measure, by including steam and other operating revenues, cost of sales - steam and other, O&M expenses, demand side management (DSM) expenses, depreciation and amortization and taxes (other than income taxes).

Results of Operations

PSCo’s net income was approximately $256$463 million for the secondthird quarter of 2018, compared with approximately $212$398 million for the same period of 2017. The increase was driven by higher electric and natural gas margins due to the impact of an interima natural gas rate increase, subject to refund,higher electric margins reflecting favorable weather and favorable weathersales growth, and increased allowance for funds used during construction (AFUDC) primarily related to the Rush Creek wind project. These items were partially offset by higher operating and maintenance (O&M) expenses, interest charges, depreciation expense and depreciation expense.property taxes.


Electric Revenues and Margin

Electric revenues and fuel and purchased power expenses are impacted by fluctuations in the price of natural gas and coal used in the generation of electricity. However, these price fluctuations have minimal impact on electric margin due to fuel recovery mechanisms that recover fuel expenses. The following table details the electric revenues and margin:
 Six Months Ended June 30 Nine Months Ended Sept. 30
(Millions of Dollars) 2018 2017 2018 2017
Electric revenues before impact of the TCJA $1,460
 $1,441
 $2,358
 $2,319
Electric fuel and purchased power (553) (568) (842) (857)
Electric margin before impact of the TCJA $907
 $873
 $1,516
 $1,462
Impact of the TCJA (offset as a reduction in income tax expense) (46) 
 (49) 
Electric margin $861
 $873
 $1,467
 $1,462

The following tables summarize the components of the changes in electric revenues and electric margin for the sixnine months ended JuneSept. 30:

Electric Revenues
(Millions of Dollars) 2018 vs. 2017 2018 vs. 2017
DSM program revenues (offset by expenses) $11
Estimated impact of weather 9
Retail sales growth, excluding weather impact 8
Non-fuel riders 7
Trading 3
Firm wholesale 3
DSM incentive 2
Fuel and purchased power cost recovery $(8) (7)
Estimated impact of weather 8
DSM program revenues (offset by expenses) 7
Trading 5
DSM incentive 2
Non-fuel riders 2
Firm wholesale 2
Other, net 1
 3
Total increase in electric revenues before impact of the TCJA $19
 $39
Impact of the TCJA (offset as a reduction in income tax expense) (46) (49)
Total decrease in electric revenues $(27) $(10)

Electric Margin
(Millions of Dollars) 2018 vs. 2017 2018 vs. 2017
DSM program revenues (offset by expenses) $11
Estimated impact of weather $8
 9
DSM program revenues (offset by expenses) 7
Trading 3
DSM incentive 2
Fuel handling and procurement 2
Retail sales growth (excluding weather impact) 8
Non-fuel riders 2
 7
Firm wholesale 2
 3
DSM incentive 2
Trading 2
Other, net 8
 12
Total increase in electric margin before impact of the TCJA $34
 $54
Impact of the TCJA (offset as a reduction in income tax expense) (46) (49)
Total decrease in electric margin $(12)
Total increase in electric margin $5


Natural Gas Revenues and Margin

Total natural gas expense varies with changing sales and the cost of natural gas. However, fluctuations in the cost of natural gas has minimal impact on natural gas margin due to natural gas cost recovery mechanisms. The following table details natural gas revenues and margin:
 Six Months Ended June 30 Nine Months Ended Sept. 30
(Millions of Dollars) 2018 2017 2018 2017
Natural gas revenues before impact of the TCJA $566
 $549
 $728
 $691
Cost of natural gas sold and transported (250) (267) (282) (304)
Natural gas margin before impact of the TCJA $316
 $282
 $446
 $387
Impact of the TCJA (offset as a reduction in income tax expense) (15) 
 (20) 
Natural gas margin $301
 $282
 $426
 $387

The following tables summarize the components of the changes in natural gas revenues and natural gas margin for the sixnine months ended JuneSept. 30:

Natural Gas Revenues
(Millions of Dollars) 2018 vs. 2017 2018 vs. 2017
Retail rate increase (interim, subject to refund) $20
Retail rate increase $36
Infrastructure and integrity riders 8
 13
Estimated impact of weather 4
 4
Retail sales growth (excluding weather impact) 2
Purchased natural gas adjustment clause recovery (16) (21)
Other, net 1
 3
Total increase in natural gas revenues before impact of the TCJA $17
 $37
Impact of the TCJA (offset as a reduction in income tax expense) (15) (20)
Total increase in natural gas revenues $2
 $17

Natural Gas Margin
(Millions of Dollars) 2018 vs. 2017 2018 vs. 2017
Retail rate increase (interim, subject to refund) $20
Retail rate increase $36
Infrastructure and integrity riders 8
 13
Estimated impact of weather 4
 4
Retail sales growth (excluding weather impact) 2
Other, net 2
 4
Total increase in natural gas margin before impact of the TCJA $34
 $59
Impact of the TCJA (offset as a reduction in income tax expense) (15) (20)
Total increase in natural gas margin $19
 $39

Non-Fuel Operating Expenses and Other Items

O&M Expenses O&M expenses increased 28 million, or 5.1 percent, for 2018 year-to-date. The year-to-date change largely reflects expense timing and increased system maintenance due to hot summer weather. The significant changes are summarized in the table below:
(Millions of Dollars) 2018 vs. 2017
Distribution costs $10
Natural gas systems damage prevention 7
Business systems and contract labor 4
Plant generation costs (4)
Other, net 11
  Total increase in O&M expenses $28

Distribution costs reflect high maintenance expenses, including vegetation management; and
Business systems and contract labor costs increased due to growing network and storage needs, cybersecurity initiatives, to support our customer strategy, and various projects and initiatives to improve business processes.

DSM Program Expenses DSM program expenses increased $8$13 million, or 13.713.8 percent, for 2018 year-to-date. The increase was due to higher recovery rates for electric and natural gas sales.increases in conservation programs to help customers reduce energy use. DSM expenses are generally recovered concurrently through riders and base rates. Timing of recovery may not correspond to the period in which costs were incurred.

Depreciation and Amortization Depreciation and amortization expense increased $6$55 million, or 2.415.8 percent, for 2018 year-to-date. The increase was primarily driven by capital expenditures due to planned system investments.investments and additional amortization of a prepaid pension asset related to the electric TCJA settlement, which is offset by lower income taxes (approximately $46 million year-to-date).

Taxes (Other than Income Taxes) Taxes (other than income taxes) increased 6.7 million, or 4.6 percent, for 2018 year-to-date. The increase was primarily due to higher property taxes in Colorado.

AFUDC, Equity and Debt AFUDC increased $19$30 million for 2018 year-to-date.  The increase was primarily due to the Rush Creek wind project.

Interest Charges Interest charges increased $9$13 million, or 9.69.1 percent, for 2018 year-to-date. The increase was primarily due to higher debt levels to fund capital investments, partially offset by refinancings at lower interest rates.


Income Taxes — Income tax expense decreased $47$111 million for the first sixnine months of 2018 compared with the same period in 2017. The decrease was primarily driven by a lower federal tax rate due to the TCJA.TCJA and lower pretax earnings and an increase in plant-related regulatory differences related to ARAM (net of deferrals). The ETR was 22.519.9 percent for the first sixnine months of 2018 compared with 36.436.2 percent for the same period of 2017. The lower ETR in 2018 is primarily due to the lower federal tax rate. See Note 4 to the consolidated financial statements.

Public Utility Regulation

Except to the extent noted below and in Note 5 to the consolidated financial statements, the circumstances set forth in Public Utility Regulation included in Item 1 of PSCo’s Annual Report on Form 10-K for the year ended Dec. 31, 2017 and Public Utility Regulation included in Item 2 of PSCo’s Quarterly Report on Form 10-Q for the quarterly periodperiods ended March 31, 2018 and June 30, 2018, appropriately represent, in all material respects, the current status of public utility regulation and are incorporated herein by reference.

Colorado Energy Plan (CEP) In 2016, PSCo filed its 2016 Electric Resource Plan (ERP) which included the estimated need for additional generation resources through spring of 2024. In 2017, PSCo filed an updated capacity need withSeptember 2018, the CPUC of 450 MW in 2023.

In 2017, PSCo and various other stakeholders filedissued a stipulation agreement proposing the CEP, an alternative plan that increaseswritten order approving PSCo’s potential capacity need up to 1,110 MW due to the proposed retirement of two coal units.

In June 2018, PSCo filed its 120-day update report with the CPUC which includes multiple portfolios and recommends a preferred CEP portfolio. PSCo's investment under the preferred CEP portfolio, would be approximately $1 billion, including investment in transmission to support the significant increase in renewable generation in the state. The preferred CEP portfolio includes the following additions as well aswhich included the retirement of the two coal-fired generation units:units, Comanche Unit 1 (in 2022) and Comanche Unit 2 (in 2025), and the following additions:
 Total Capacity PSCo's Ownership
Wind generation1,100 MW 500 MW
Solar generation700 MW 
Battery storage275 MW 
Natural gas generation380 MW 380 MW

On July 13, 2018, the Independent Evaluator (IE)PSCo is required to file a CPCN for the ERP filed their report onowned wind generation, the process, modeling and evaluationpurchase of the various offers received through the RFP process.  Generally, the IE report was favorable to the process employednatural gas generation facility and the outcomes includedtransmission investment, which is anticipated for later this year. PSCo’s investment is expected to be approximately $1 billion, including investments in required transmission to support the significant increase in renewable generation in the modeling.  Certain recommendations for future ERP processes were provided with a primary focus regarding enhanced modeling of new resource types such as battery storage.
On July 23, 2018, various stakeholders commented on the 120-day update report for the ERP and the CEP. Many community, advocate and developer interests supported the CEP, while certain stakeholders opposed the CEP and the associated early coal plant retirements. The CPUC staff indicated that PSCo’s preferred CEP plan is a valid option, but expressed concerns on the saving assumptions, complexity of modeling and the utilization of production tax credits.

A CPUC decision is anticipated in September 2018.state.

Public Utility Regulatory Policies Act (PURPA) Enforcement Complaint againstEVRAZ — In October 2018, the CPUC — Sustainable Power Group, LLC (sPower) has proposed to construct over 1,500 MW of solar and wind generationapproved the application for an agreement with EVRAZ, a steelmaker in Colorado, to stabilize its rates for over 23 years through a specific customer contract and the development of a 240 MW, customer-sited solar facility. EVRAZ is seekingPSCo’s largest customer and sought a long-term solution from state and local authorities in order to require PSCo to contract for these resources under PURPA. In March 2017, sPower filed a complaint for declaratorymaintain and injunctive reliefgrow its operations in the United States District Court for the District of Colorado (District Court) requesting that the court find a December 2016 CPUC ruling that a qualifying facility must be a successful bidder in a PSCo resource acquisition bidding process violated PURPA and FERC rules. In June 2018, the court denied a motion by the CPUC to dismiss. The case remains pending further action from the court.


Open Access Transmission Tariff (OATT) Reform — In May 2018, the FERC denied a request by PSCo to amend its OATT to allow large generating interconnection agreements to be suspended by the generator only due to a force majeure event, rather than allowing suspension for up to 36 months for any reason.  PSCo requested the changes to facilitate more efficient processing of generator interconnection requests.  PSCo has initiated a process to achieve broader generator interconnection queue reform and anticipates requesting additional OATT changes later in 2018.  In April, 2018, the FERC had issued a final rule requiring generator interconnection OATT queue reforms in addition (but generally complimentary) to reforms PSCo already requested. PSCo currently has more than 22,000 MW of new generator projects in its interconnection queue.  The broader interconnection queue reforms are intended to allow generators to proceed to interconnection on a “first ready, first served” basis, similar to the processes already use in MISO.Colorado.

Boulder, Colorado Municipalization — In 2011, City of Boulder, Colorado (Boulder) voters passed a ballot measure authorizing the formation of an electric municipal utility, subject to certain conditions. Since that time, there have been various legal proceedings in multiple venues with jurisdiction over Boulder’s plan. In 2014, the Boulder City Council passed an ordinance to establish an electric utility. PSCo challenged the formation of this utility as premature and the Colorado Court of Appeals ruled in PSCo’s favor, vacating a lower court decision. In June 2018, the Colorado Supreme Court rejected Boulder’s request to dismiss the case and ruled that the case be remanded for hearing at theit to Boulder District Court (District Court).where the litigation process has started.

Boulder has filed multiple separation applications with the CPUC, which have been challenged by PSCo and other intervenors. In September 2017, the CPUC issued a written decision, agreeing with several key aspects of PSCo’s position. The CPUC approved the designation of some electrical distribution assets for transfer, subject to Boulder completing certain filings. In July 2018,Those filings are due to be submitted in the CPUC approved Boulder and PSCo’s joint request to extend the time by which these filings would be due until Aug. 24,fourth quarter of 2018. Boulder does not have authorization from the CPUC to initiate a condemnation proceeding at this time.

Summary of Recent Federal Regulatory Developments

FERC

The FERC has jurisdiction over rates for electric transmission service in interstate commerce and electricity sold at wholesale, hydro facility licensing, natural gas transportation, asset transactions and mergers, accounting practices and certain other activities of PSCo, including enforcement of North American Electric Reliability Corporation mandatory electric reliability standards. State and local agencies have jurisdiction over many of PSCo’s activities, including regulation of retail rates and environmental matters. See additional discussion in the summary of recent federal regulatory developments and public utility regulation sections of the PSCo Annual Report on Form 10-K for the year ended Dec. 31, 2017 and Quarterly ReportReports on Form 10-Q for the quarterly periodperiods ended March 31, 2018 and June 30, 2018. In addition to the matters discussed below, see Note 5 to the consolidated financial statements for a discussion of other regulatory matters.

Xcel Energy, which includes PSCo, attempts to mitigate the risk of regulatory penalties through formal training on prohibited practices and a compliance function that reviews interaction with the markets under FERC and Commodity Futures Trading Commission jurisdictions. Public campaigns are conducted to raise awareness of the public safety issues of interacting with our electric systems. While programs to comply with regulatory requirements are in place, there is no guarantee the compliance programs or other measures will be sufficient to ensure against violations.

Item 4 — CONTROLS AND PROCEDURES

Disclosure Controls and Procedures

PSCo maintains a set of disclosure controls and procedures designed to ensure that information required to be disclosed in reports that it files or submits under the Securities Exchange Act of 1934 is recorded, processed, summarized, and reported within the time periods specified in SEC rules and forms. In addition, the disclosure controls and procedures ensure that information required to be disclosed is accumulated and communicated to management, including the chief executive officer (CEO) and chief financial officer (CFO), allowing timely decisions regarding required disclosure. As of JuneSept. 30, 2018, based on an evaluation carried out under the supervision and with the participation of PSCo’s management, including the CEO and CFO, of the effectiveness of its disclosure controls and the procedures, the CEO and CFO have concluded that PSCo’s disclosure controls and procedures were effective.

Internal Control Over Financial Reporting

No changes in PSCo’s internal control over financial reporting occurred during the most recent fiscal quarter that materially affected, or are reasonably likely to materially affect, PSCo’s internal control over financial reporting.

Part II — OTHER INFORMATION


Item 1LEGAL PROCEEDINGS

PSCo is involved in various litigation matters that are being defended and handled in the ordinary course of business. The assessment of whether a loss is probable or is a reasonable possibility, and whether the loss or a range of loss is estimable, often involves a series of complex judgments about future events. Management maintains accruals for such losses that are probable of being incurred and subject to reasonable estimation. Management is sometimes unable to estimate an amount or range of a reasonably possible loss in certain situations, including but not limited to when (1) the damages sought are indeterminate, (2) the proceedings are in the early stages, or (3) the matters involve novel or unsettled legal theories. In such cases, there is considerable uncertainty regarding the timing or ultimate resolution of such matters, including a possible eventual loss.

Additional Information

See Note 6 to the consolidated financial statements for further discussion of legal claims and environmental proceedings. See Part I Item 2 and Note 5 to the consolidated financial statements for a discussion of proceedings involving utility rates and other regulatory matters.

Item 1A — RISK FACTORS

PSCo’s risk factors are documented in Item 1A of Part I of its Annual Report on Form 10-K for the year ended Dec. 31, 2017, which is incorporated herein by reference. There have been no material changes from the risk factors previously disclosed in the Form 10-K.

Item 6 EXHIBITS
*Indicates incorporation by reference


101The following materials from PSCo’s Quarterly Report on Form 10-Q for the quarter ended JuneSept. 30, 2018 are formatted in XBRL (eXtensible Business Reporting Language):  (i) the Consolidated Statements of Income, (ii) the Consolidated Statements of Comprehensive Income (iii) the Consolidated Statements of Cash Flows, (iv) the Consolidated Balance Sheets, (v) Notes to Consolidated Financial Statements, and (vi) document and entity information.


SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

  Public Service Company of Colorado
   
July 27,Oct. 26, 2018By:/s/ JEFFREY S. SAVAGE
  Jeffrey S. Savage
  Senior Vice President, Controller
  (Principal Accounting Officer)
   
  /s/ ROBERT C. FRENZEL
  Robert C. Frenzel
  Executive Vice President, Chief Financial Officer and Director
  (Principal Financial Officer)


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