CMS Energy (CMS) 8-K Regulation FD Disclosure

Exhibit 99.1

Investor Meetings May 2011

This presentation is made as of the date hereof and contains "forward-looking statements" as defined in Rule 3b-6 of the Securities Exchange Act of 1934, as amended, Rule 175 of the Securities Act of 1933, as amended, and relevant legal decisions. The forward-looking statements are subject to risks and uncertainties. They should be read in conjunction with "FORWARD- LOOKING STATEMENTS AND INFORMATION" and "RISK FACTORS" sections of CMS Energy's and Consumers Energy's Form 10-K for the year ended December 31 and as updated in subsequent 10-Qs. CMS Energy's and Consumers Energy's "FORWARD-LOOKING STATEMENTS AND INFORMATION" and "RISK FACTORS" sections are incorporated herein by reference and discuss important factors that could cause CMS Energy's and Consumers Energy's results to differ materially from those anticipated in such statements. CMS Energy and Consumers Energy undertake no obligation to update any of the information presented herein to reflect facts, events or circumstances after the date hereof. The presentation also includes non-GAAP measures when describing CMS Energy's results of operations and financial performance. A reconciliation of each of these measures to the most directly comparable GAAP measure is included in the appendix and posted on our website at www.cmsenergy.com. CMS Energy expects 2011 reported earnings to be about the same as adjusted earnings. Reported earnings could vary because of several factors. CMS Energy is not providing reported earnings guidance reconciliation because of the uncertainties associated with those factors. 1

Business Model Strong (5% to 7% growth) . . . . Financial Use NOLs to eliminate need for equity Grow Operating Cash Flow and EPS 5% - 7% Business Invest in Utility Create Jobs Enhance Customer Value Moderate Rate Increase 2 Consistent financial performance Fair and timely regulation Utility investment Customer value Safe, excellent operations .. . . . and sustainable with moderate rate increases <2%.

First Quarter Summary First Quarter adjusted EPS (non-GAAP) 51¢; up 13¢ or 34% from 2010 Growth model working well Strong customer demand for investment projects Grows rate base 5% - 7% Grows earnings without new equity dilution Low rate increases make plan sustainable Reaffirm full year adjusted EPS (non-GAAP) guidance 3

Consumers Energy Fourth largest combination utility in the United States 1.8 million electric and 1.7 million gas customers 9,200 MW of owned and purchased generation capacity Renewable energy 5% of present supply 307 Bcf of gas storage capacity Ludington Pumped Storage B C Cobb J H Campbell D E Karn J C Weadock Mio Alcona Cooke Foote Loud 5 Channels Hodenpyl Tippy Rogers Hardy Croton Webber Allegan Electric Gas Combination Overview Territory Investment growth balances responsible rate increases with attractive earnings growth. Zeeland 4 J R Whiting

Capital Investment . . . . 2010 2011 2012 2013 2014 2015 Average Rate Base (bils) $10.3 $10.9 $11.6 $12.4 $13.3 0 Rate Base Bils $ Present Rate Base 5%-7% Reliability & Others Renewables Smart Grid Environmental Maintenance Depreciation .. . . . provides earnings growth. Utility Investment $6.4 Billion 2011-2015 5

Ludington Upgrade to 2,200 MW . . . . 6 .. . . . underway. Increase capacity by 15% Increase efficiency by 5% Operate for 30 years before next major overhaul $800 million total investment over 10 years Consumers Energy share $400 million

$1.5 Billion Environmental Investment . . . . 7 Environmental emission reductions better than plan Regulatory outlook improved GHG Regulation - minimal impact anticipated .. . . . over next 5 years.

Environmental Spending 2011-2015 . . . . 8 Mercury SO2 NOx Emissions Reductions Expenditures .. . . . significantly reduced air emissions.

Renewable Energy Plans . . . . Michigan energy law requires: 10% renewables by 2015 Purchase 50% and build 50% Renewable energy surcharge reduced $55 million annually Still plan to invest $650 million over next five years, primarily on wind power .. . . . at lower customer costs while maintaining wind investment. Renewable Facilities Proposed Company-owned Wind Facilities New Power Purchase Agreements (287 MW) ^ 9 ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ Cross Winds Energy Park Lake Winds Energy Park ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ Upper Peninsula

10 Smart Grid Deployment . . . . .. . . . improves overall financial viability. Billing Customer Information Outage Management Work and Asset Management Enterprise Applications MDM/MDUS Total project cost $750 million Meter deployment begins early 2012 Removed deployment of gas only meters Minimize upfront IT system cost by installing only basic functionality Expanded functions installed later Improved ability to scale plan

Intense Customer Focus . . . . 11 .. . . . continues as core to success. 2011-2015 Estimated Annual Average Base Rate Increases Productivity Initiatives Customer Value Initiative Maximize Energy Optimization Improve system reliability Competitive rates

Focus on Cost Improvement . . . . Fuel Western coal - $250 million Base Rates and Surcharges Benefit plans - $30 million SAP system efficiencies - $40 million Reduced workforce - $30 million Reduced customer renewable energy surcharge - $55 million 12 .. . . . to minimize customer rate increases. 10% Reduction in Workforce Workforce Resizing Recent Cost Reductions

Regulatory Progress . . . . .. . . . supports growth. 2009 Filed $214 M Self-Imp $179 M Order $139 M 2010 Filed $178 M Self-Imp $150 M Order $146 M 2009 Filed $114 M Self-Imp $89 M Order $66 M 2010 Filed $55 M 78% 97% 74% 2008 2009 2010 2011 Electric Gas 2008 2009 2010 2011 Filed New Renewable Plan $55 M Reduction 2011 13 File Self-Imp Settlement

Gas Rate Case 14 CE Self-Implement Staff Self-Imp. Revised Staff Revised Settlement Filing Date 8/13/10 1/6/11 1/24/11 2/8/11 4/4/11 5/11 ROE 11% 11% 10.1% 10.55% 10.1% Rate Base $2.90B $2.90B $2.86B $2.90B $2.88B Sales Update Optional No No No No (Millions) $ $88 Sales MPSC Delays Self-Implementation 2/8/11 In Principle

Best in Class Risk Management . . . . .. . . . mitigates volatility. Old Opportunities Old Risks Decouple Decouple Cost Performance Reinvest 15 EPS 5% - 7% Base Rates <2%

_ _ _ _ _ a Adjusted EPS (non-GAAP) excluding MTM in 2004-2006 b $1.25 excluding discontinued Exeter operations and accounting changes related to Convertible debt and restricted stock 16 8% CAGR .. . . . paying off. Focus on Customers and Owners . . . . Dividend Annual ¢/share Payout 25% 30% 40% 84¢ +68% $1.20 $1.25 $1.26 $1.35 5%-7% Growth $1.44 $1.21 b Actual a Guidance

Electric Sales (weather adjusted) . . . . 2011 Sales (vs 2010) .. . . . recovering, conservative outlook. Electric Sales 0 7% decline 1979 to 1982 6% decline 2007 to 2009 Total +2.5% Up 9% 1983 &1984 Up 4% 2010 & 2011 17

Michigan 2010 Census Results 18 Population Change by County: 2000-2010 15-25% 5-15 0-5 < -10 Not in service territory Service Territory Change Consumers +3% Non-Consumers - 7 State of Michigan - 1 > -10

2011 Adjusted EPS (non-GAAP) . . . . First Quarter Nine Months To Go 13 (5) $1.44 . $1.36 Gas Weather Old Rates Old Rates New Rates 2011 Gas weather (cold) 4 2010 Gas weather (mild)2 2010 Gas (w/o decoupling) 3 Electric margin 3 Utility OM (10) Total 12 (reliability outages) Investment (7) PA141 (3) First Quarter Storms (3) Financing and other 1 First Quarter Total (19) Investment (3) Enterprises (3) Total (9) .. . . .. . . . guidance reaffirmed. 19

Cash Flow and EPS Grow 5% to 7% . . . . 20 .. . . . driven by investment. Amount (bils) $ Gross operating cash flow a up $0.1 billion per year $1.8 Interest Working capital and taxes Base Investment $1.3 $1.6 $1.6 $1.7 $1.5 $1.9 Cash flow before dividend Investment choices _ _ _ _ _ a Non-GAAP

Liquidity Strong With Recent Renewals . . . . 21 .. . . . and substantial cash as of March 31, 2011. Renewal Availability Capacity $2.3 Billion $2.0 Billion Among first 5-year term revolvers since 2007 CMS Energy 5-year revolver 5-year revolver 3-year revolver Letter of Credit AR Facility Consumers Energy Cash 2011 2011 2013 2016 2016 $550 mils 500 150 250 800 30 $550 mils 210 150 250 800

2011 Sensitivities . . . . _ _ _ _ _ * Less than 0.5¢ or $500,000 .. . . . partly mitigated. Annual Impact Annual Impact Annual Impact Sensitivity EPS OCF (mils) Sales (weather adjusted) Electric (37,760 Gwh) Gas (282 Bcf) + 1% + 1 $ 0 + 0.01 + $20 + 5 Gas prices (NYMEX) + 1.00 0.01 60 Uncollectible accounts (mils) + 5 0.01 * ROE (authorized) Electric (10.7%) Gas (10.55%) + 50 bps + 50 + 0.06 + 0.02 + 25 + 10 Stock price (dilution) $1 share + 0.01 0 22 - + - + - +

Business Model Strong (5% to 7% growth) . . . . Financial Use NOLs to eliminate need for equity Grow Operating Cash Flow and EPS 5% - 7% Business Invest in Utility Create Jobs Enhance Customer Value Moderate Rate Increase 23 Consistent financial performance Fair and timely regulation Utility investment Customer value Safe, excellent operations .. . . . and sustainable with moderate rate increases <2%.

Appendix

Electric Customer Base Diversified . . . . Hemlock Semiconductor General Motors State of Michigan Meijer Incorporated Nexteer Automotive Corporation Packaging Corporation of America Gerdau MacSteel Denso International Spectrum Health City of Grand Rapids Percent of 2010 electric gross margin is 2% Top Ten Customers Residential Commercial Autos Industrial Other (including ROA) 0.48 0.31 0.04 0.1 0.07 $1.95 Billion .. . . . "Autos" only 4% of gross margin. 2010 Electric Gross Margin Note: "Autos" includes 180 Business Partners identified by customer account managers 25

26 2011 First Quarter EPS Adjusted EPS (non-GAAP) for First Quarter 2011 up 13¢ from 2010. By Business Segment Results 13¢ 13¢

Federal Tax Benefits 27

Consumers Capital Expenditures 28

2011 Cash Flow Forecast (non-GAAP) CMS Energy Parent Consumers Energy _ _ _ _ _ a Includes other _ _ _ _ _ b Includes cost of removal and capital leases $210 29

Michigan Public Service Commission (MPSC) Composed of three members appointed by the Governor with the advice and consent of the Senate Appointed to serve staggered six-year terms No more than two Commissioners may represent the same political party One Commissioner is designated as Chairman by the Governor Orjiakor Isiogu, Chairman Appointed: 9/9/07 Term Ends: 7/2/13 Democrat Monica Martinez, Commissioner Appointed: 7/3/05 Term Ends: 7/2/11 Democrat Greg White, Commissioner Appointed: 12/4/09 Term Ends: 7/2/15 Independent 31

GAAP Reconciliation

CMS ENERGY CORPORATION
Earnings Per Share By Year GAAP Reconciliation
(Unaudited)

	2003			2004			2005			2006			2007			2008			2009			2010
Reported earnings (loss) per share — GAAP		($0.30	)	$	0.64			($0.44	)		($0.41	)		($1.02	)	$	1.20		$	0.91		$	1.28
After-tax items:
Electric and gas utility		0.21			(0.39	)		—			—			(0.07	)		0.05			0.33			0.03
Enterprises		0.74			0.62			0.04			(0.02	)		1.25			(0.02	)		0.09			(0.03	)
Corporate interest and other		0.16			(0.03	)		0.04			0.27			(0.32	)		(0.02	)		0.01			*
Discontinued operations (income) loss		(0.16	)		0.02			(0.07	)		(0.03	)		0.40			(*	)		(0.08	)		0.08
Asset impairment charges, net		—			—			1.82			0.76			0.60			—			—			—
Cumulative accounting changes		0.16			0.01			—			—			—			—			—			—
Adjusted earnings per share, including MTM — non-GAAP	$	0.81		$	0.87		$	1.39		$	0.57		$	0.84		$	1.21	(a)	$	1.26		$	1.36
Mark-to-market impacts					0.03			(0.43	)		0.51
Adjusted earnings per share, excluding MTM — non-GAAP	NA			$	0.90		$	0.96		$	1.08		NA			NA			NA			NA

*	Less than $500 thousand or $0.01 per share.
(a)	$1.25 excluding discontinued Exeter operations and accounting changes related to convertible debt and restricted stock.

CMS Energy
Reconciliation of Gross Operating Cash Flow to GAAP Operating Activities
(unaudited)
(mils)

	2009			2010			2011			2012			2013			2014			2015
Consumers Operating Income + Depreciation & Amortization	$	1,248		$	1,498		$	1,520		$	1,601		$	1,657		$	1,757		$	1,872
Enterprises Project Cash Flows		16			39			40			35			47			47			46
Gross Operating Cash Flow	$	1,264		$	1,537		$	1,560		$	1,636		$	1,704		$	1,804		$	1,918
Other operating activities including taxes, interest payments and working capital		(416	)		(578	)		(410	)		(406	)		(472	)		(439	)		(835	)
Net cash provided by operating activities	$	848		$	959		$	1,150		$	1,230		$	1,232		$	1,365		$	1,083

CMS ENERGY CORPORATION
Earnings By Quarter and Year GAAP Reconciliation
(Unaudited)

(In millions, except per share amounts)	2010
	1Q		2Q			3Q			4Q		YTD Dec
Reported net income — GAAP	$	85	$	80		$	134		$	25	$	324
After-tax items:
Electric and gas utility		6		*			—			—		6
Enterprises		1		(31	)		(2	)		24		(8	)
Corporate interest and other		*		*			—			*		*
Discontinued operations loss		1		16			*			6		23
Adjusted income — non-GAAP	$	93	$	65		$	132		$	55	$	345
Average shares outstanding, basic		228.0		228.2			229.0			240.7		231.5
Average shares outstanding, diluted		246.5		247.6			254.7			258.4		252.9
Reported earnings per share — GAAP	$	0.34	$	0.32		$	0.53		$	0.09	$	1.28
After-tax items:
Electric and gas utility		0.03		*			—			—		0.03
Enterprises		*		(0.13	)		(0.01	)		0.10		(0.03	)
Corporate interest and other		*		*			—			*		*
Discontinued operations loss		0.01		0.07			*			0.02		0.08
Adjusted earnings per share — non-GAAP	$	0.38	$	0.26		$	0.52		$	0.21	$	1.36

(In millions, except per share amounts)	2011
	1Q
Reported net income — GAAP	$	135
After-tax items:
Electric and gas utility		—
Enterprises		*
Corporate interest and other		—
Discontinued operations (income) loss		(2	)
Adjusted income — non-GAAP	$	133
Average shares outstanding, basic		250.0
Average shares outstanding, diluted		261.7
Reported earnings per share — GAAP	$	0.52
After-tax items:
Electric and gas utility		—
Enterprises		*
Corporate interest and other		—
Discontinued operations (income) loss		(0.01	)
Adjusted earnings per share — non-GAAP	$	0.51

Note: Year-to-date (YTD) EPS may not equal sum of quarters due to share count differences.

CMS Energy Corporation
Earnings Segment Results GAAP Reconciliation
(Unaudited)

	Three Months Ended
March 31	2011			2010
Electric Utility
Reported	$	0.25		$	0.16
Downsizing Program and Other, net		—			0.02
Adjusted	$	0.25		$	0.18
Gas Utility
Reported	$	0.33		$	0.27
Downsizing Program and Other, net		—			0.01
Adjusted	$	0.33		$	0.28
Enterprises
Reported	$	0.01		$	0.04
Downsizing Program and Other, net		*			*
Adjusted	$	0.01		$	0.04
Corporate Interest and Other
Reported	$	(0.08	)	$	(0.12	)
Downsizing Program and Other, net		—			*
Adjusted	$	(0.08	)	$	(0.12	)
Discontinued Operations
Reported	$	0.01		$	(0.01	)
Discontinued Operations (Income) Loss		(0.01	)		0.01
Adjusted	$	—		$	—
Totals
Reported	$	0.52		$	0.34
Discontinued Operations (Income) Loss		(0.01	)		0.01
Downsizing Program and Other, net		*			0.03
Adjusted	$	0.51		$	0.38
Average Common Shares Outstanding — Diluted (in millions)		261.7			246.5

* Less than $0.01 per share.

Consumers Energy
2011 Forecasted Cash Flow GAAP Reconciliation (in millions) (unaudited)

				Reclassifications From Sources and Uses to Statement of Cash Flows
Presentation Sources and Uses				Tax			Interest			Other Working			Capital			Securitization			Preferred			Common			Consolidated Statements of Cash Flows
	non-GAAP			Sharing			Payments			Capital			Lease Pymts			Debt Pymts			Dividends			Dividends			GAAP
Description	Amount			Operating			as Operating			as Investing			as Financing			as Financing			as Financing			as Financing			Amount			Description
Cash at year end 2010	$	71		$	—		$	—		$	—		$	—		$	—		$	—		$	—		$	71		Cash at year end 2010
Sources
Operating	$	1,520		$	50		$	(233	)	$	—		$	23		$	37		$	—		$	—		$	1,397
Other working capital		(15	)		—			—			20			—			—			—			—			5		Net cash provided by
Sources	$	1,505		$	50		$	(233	)	$	20		$	23		$	37		$	—		$	—		$	1,402		operating activities
Uses
Interest and preferred dividends	$	(235	)	$	—		$	233		$	(20	)	$	—		$	—		$	2		$	—		$	(20	)
Capital expenditures		(1,065	)		—			—			—			—			—			—			—			(1,065	)
Dividends/tax sharing to CMS		(315	)		(50	)		—			—			—			—			—			365			—		Net cash provided by
Uses	$	(1,615	)	$	(50	)	$	233		$	(20	)	$	—		$	—		$	2		$	365		$	(1,085	)	investing activities
																												Cash flow from
Cash flow	$	(110	)	$	—		$	—		$	—		$	23		$	37		$	2		$	365		$	317		operating and
																												investing activities
Financing
Equity	$	125		$	—		$	—		$	—		$	—		$	—		$	—		$	—		$	125
New Issues		—			—			—			—			—			—			—			—			—
Retirements		—			—			—			—			(23	)		(37	)		—			(365	)		(425	)
Net short-term financing & other		(47	)		—			—			—			—			—			(2	)		—			(49	)	Net cash provided by
Financing	$	78		$	—		$	—		$	—		$	(23	)	$	(37	)	$	(2	)	$	(365	)	$	(349	)	financing activities
Net change in cash	$	(32	)	$	—		$	—		$	—		$	—		$	—		$	—		$	—		$	(32	)	Net change in cash
Cash at year end 2011	$	39		$	—		$	—		$	—		$	—		$	—		$	—		$	—		$	39		Cash at year end 2011

CMS Energy Parent
2011 Forecasted Cash Flow GAAP Reconciliation (in millions) (unaudited)

				Reclassifications From Sources and Uses to Statement of Cash Flows
Presentation Sources and Uses				Interest			Overheads &			Other			Preferred		Cash From			Consolidated Statements of Cash Flows
	non-GAAP			Payments			Tax Payments			Uses (a)			Dividends		Consolidated			GAAP
Description	Amount			as Operating			as Operating			as Operating			as Financing		Companies			Amount			Description
Cash at year end 2010	$	163		$	—		$	—		$	—		$	—	$	13		$	176		Cash at year end 2010
Sources
Consumers Energy dividends/tax sharing	$	315		$	(125	)	$	(15	)	$	—		$	—	$	—		$	175
Enterprises		35			—			—			(90	)		—		7			(48	)	Net cash provided by operating activities
Sources	$	350		$	(125	)	$	(15	)	$	(90	)	$	—	$	7		$	127
Uses
Interest and preferred dividends	$	(125	)	$	125		$	—		$	—		$	—	$	—		$	—
Overhead and Federal tax payments		(15	)		—			15			—			—		—			—
Equity infusions		(125	)		—			—			90			—		(60	)		(95	)	Net cash provided by investing activities
Uses (a)	$	(355	)	$	125		$	15		$	90		$	—	$	(60	)	$	(185	)
																					Cash flow from operating and investing activities
Cash flow	$	(5	)	$	—		$	—		$	—		$	—	$	(53	)	$	(58	)
Financing and dividends
New Issues	$	250		$	—		$	—		$	—		$	—	$	53		$	303
Retirements		(150	)		—			—			—			—		—			(150	)
Net short-term financing & other		20			—			—			—			—		—			20
Common dividend		(210	)		—			—			—			—		—			(210	)	Net cash provided by financing activities
Financing	$	(90	)	$	—		$	—		$	—		$	—	$	53		$	(37	)
Net change in cash	$	(95	)	$	—		$	—		$	—		$	—	$	—		$	(95	)	Net change in cash
Cash at year end 2011	$	68		$	—		$	—		$	—		$	—	$	13		$	81		Cash at year end 2011

(a) Includes other and roundings

Consolidated CMS Energy
2011 Forecasted Consolidation of Consumers Energy and CMS Energy Parent Statements of Cash Flow (in millions) (unaudited)

							Eliminations/Reclassifications to Arrive at the Consolidated Statement of Cash Flows
Statements of Cash Flows							Consumers			Consumers			Equity
	Consumers			CMS Parent			Common Dividend			Preferred Dividend			Infusions to			Consolidated Statements of Cash Flows
Description	Amount			Amount			as Financing			as Operating			Consumers			Amount			Description
Cash at year end 2010	$	71		$	176		$	—		$	—		$	—		$	247		Cash at year end 2010
Net cash provided by operating activities	$	1,402		$	127		$	(365	)	$	(2	)	$	—		$	1,162		Net cash provided by operating activities
Net cash provided by investing activities		(1,085	)		(185	)		—			—			125			(1,145	)	Net cash provided by investing activities
Cash flow from operating and investing activities	$	317		$	(58	)	$	(365	)	$	(2	)	$	125		$	17		Cash flow from operating and investing activities
Net cash provided by financing activities	$	(349	)	$	(37	)	$	365		$	2		$	(125	)	$	(144	)	Net cash provided by financing activities
Net change in cash	$	(32	)	$	(95	)	$	—		$	—		$	—		$	(127	)	Net change in cash
Cash at year end 2011	$	39		$	81		$	—		$	—		$	—		$	120		Cash at year end 2011