Vertex (VERX) 10-Q 10 May 23 2023 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2023	May 05, 2023
Document Information:
Document Type	10-Q
Document Period End Date	Mar. 31, 2023
Document Quarterly Report	true
Document Transition Report	false
Entity File Number	001-39413
Entity Registrant Name	Vertex, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	23-2081753
Entity Address, Address Line One	2301 Renaissance Blvd
Entity Address, City or Town	King of Prussia
Entity Address State Or Province	PA
Entity Address, Postal Zip Code	19406
City Area Code	800
Local Phone Number	355-3500
Title of 12(b) Security	Class A Common Stock, Par Value $0.001 Per Share
Trading Symbol	VERX
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Shell Company	false
Entity Central Index Key	0001806837
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q1
Amendment Flag	false
Class A
Document Information:
Entity Common Stock, Shares Outstanding		53,860,965
Class B
Document Information:
Entity Common Stock, Shares Outstanding		97,718,000

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 68,643	$ 91,803
Funds held for customers	25,972	14,945
Accounts receivable, net of allowance of $10,641 and $9,554, respectively	102,760	102,885
Prepaid expenses and other current assets	22,536	20,383
Investment securities available-for-sale, current, at fair value (amortized cost of $11,552 and $11,220, respectively)	11,524	11,173
Total current assets	231,435	241,189
Property and equipment, net of accumulated depreciation	117,444	115,768
Capitalized software, net of accumulated amortization	38,790	39,012
Goodwill and other intangible assets	259,303	257,023
Deferred commissions	15,921	15,463
Deferred income tax asset	43,542	30,938
Operating lease right-of-use assets	16,462	17,187
Other assets	2,621	2,612
Total assets	725,518	719,192
Current liabilities:
Current portion of long-term debt	2,500	2,188
Accounts payable	17,420	14,329
Accrued expenses	55,896	38,234
Customer funds obligations	23,110	12,121
Accrued salaries and benefits	15,142	10,790
Accrued variable compensation	8,045	23,729
Deferred compensation, current	2,352	2,809
Deferred revenue, current	276,004	268,847
Current portion of operating lease liabilities	3,141	4,086
Current portion of finance lease liabilities	75	103
Deferred purchase consideration, current	9,924	19,824
Purchase commitment and contingent consideration liabilities, current	8,340	6,149
Total current liabilities	421,949	403,209
Deferred revenue, net of current portion	7,112	10,289
Debt, net of current portion	46,093	46,709
Operating lease liabilities, net of current portion	20,057	20,421
Finance lease liabilities, net of current portion		10
Purchase commitment and contingent consideration liabilities, net of current portion	6,813	8,412
Deferred other liabilities	19	417
Total liabilities	502,043	489,467
Commitments and contingencies (Note 11)
Stockholders' equity:
Preferred shares, $0.001 par value, 30,000 shares authorized; no shares issued and outstanding
Additional paid in capital	253,566	244,820
(Accumulated deficit) retained earnings	(5,625)	12,507
Accumulated other comprehensive loss	(24,617)	(27,752)
Total stockholders' equity	223,475	229,725
Total liabilities and stockholders' equity	725,518	719,192
Class A
Stockholders' equity:
Common stock	53	50
Class B
Stockholders' equity:
Common stock	$ 98	$ 100

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) shares in Thousands, $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Allowance for accounts receivable	$ 10,641	$ 9,554
Amortized cost	$ 11,552	$ 11,220
Preferred stock par value (per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	30,000	30,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Class A
Common stock par value (per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	300,000	300,000
Common stock, shares issued (in shares)	53,586	50,014
Common stock, shares outstanding (in shares)	53,586	50,014
Class B
Common stock par value (per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	150,000	150,000
Common stock, shares issued (in shares)	97,718	100,307
Common stock, shares outstanding (in shares)	97,718	100,307

Condensed Consolidated Statemen

Condensed Consolidated Statements of Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Revenues:
Total revenues	$ 132,751	$ 114,984
Cost of revenues:
Total cost of revenues	51,747	44,866
Gross profit	81,004	70,118
Operating expenses:
Research and development	15,862	9,633
Selling and marketing	35,736	27,452
General and administrative	34,310	28,757
Depreciation and amortization	3,741	2,960
Other operating expense, net	284	848
Total operating expenses	89,933	69,650
(Loss) income from operations	(8,929)	468
Interest expense, net	(350)	(6)
(Loss) income before income taxes	(8,579)	474
Income tax expense	9,553	808
Net loss	(18,132)	(334)
Other comprehensive (income) loss:
Foreign currency translation adjustments and revaluations, net of tax	(3,122)	2,049
Unrealized gain on investments, net of tax	(13)
Total other comprehensive (income) loss, net of tax	(3,135)	2,049
Total comprehensive loss	(14,997)	(2,383)
Software subscriptions
Revenues:
Total revenues	111,014	97,131
Cost of revenues:
Total cost of revenues	37,403	32,913
Services
Revenues:
Total revenues	21,737	17,853
Cost of revenues:
Total cost of revenues	14,344	11,953
Class A
Other comprehensive (income) loss:
Net loss attributable to stockholders, basic	$ (6,072)	$ (95)
Net loss per share, basic (in dollars per share)	$ (0.12)	$ 0
Weighted average common stock, basic (in shares)	50,456	42,349
Net loss attributable to stockholders, diluted	$ (6,072)	$ (95)
Net loss per share, diluted (in dollars per share)	$ (0.12)	$ 0
Weighted average common stock, diluted (in shares)	50,456	42,349
Class B
Other comprehensive (income) loss:
Net loss attributable to stockholders, basic	$ (12,060)	$ (239)
Net loss per share, basic (in dollars per share)	$ (0.12)	$ 0
Weighted average common stock, basic (in shares)	100,221	106,807
Net loss attributable to stockholders, diluted	$ (12,060)	$ (239)
Net loss per share, diluted (in dollars per share)	$ (0.12)	$ 0
Weighted average common stock, diluted (in shares)	100,221	106,807

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Changes in Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Common Stock Class A	Common Stock Class B	Additional paid in capital.	Retained Earnings	Accumulated Other Comprehensive Loss	Class A	Class B	Total
Balance at Dec. 31, 2021	$ 42	$ 107	$ 222,621	$ 24,811	$ (17,497)			$ 230,084
Balance (in shares) at Dec. 31, 2021	42,286	106,807
Exercise of stock options, net			278					278
Exercise of stock options, net (in shares)	272					272
Shares issued upon vesting of Restricted Stock Units, net			(15)					(15)
Shares issued upon vesting of Restricted Stock Units, net (in shares)	3
Stock-based compensation expense			4,867					4,867
Foreign currency translation adjustments and revaluations, net of tax					(2,049)			(2,049)
Net loss				(334)				(334)
Balance at Mar. 31, 2022	$ 42	$ 107	227,751	24,477	(19,546)			232,831
Balance (in shares) at Mar. 31, 2022	42,561	106,807
Balance at Dec. 31, 2022	$ 50	$ 100	244,820	12,507	(27,752)			229,725
Balance (in shares) at Dec. 31, 2022	50,014	100,307				50,014	100,307
Exercise of stock options, net	$ 1		1,279					1,280
Exercise of stock options, net (in shares)	592					592
Shares issued upon vesting of Restricted Stock Units, net			(3,471)					(3,471)
Shares issued upon vesting of Restricted Stock Units, net (in shares)	391
Stock-based compensation expense			10,938					10,938
Class B shares exchanged for Class A shares	$ 2	$ (2)
Class B shares exchanged for Class A shares (in shares)	2,589	(2,589)
Foreign currency translation adjustments and revaluations, net of tax					3,122			3,122
Unrealized gain from available-for-sale investments, net of tax					13			13
Net loss				(18,132)				(18,132)
Balance at Mar. 31, 2023	$ 53	$ 98	$ 253,566	$ (5,625)	$ (24,617)			$ 223,475
Balance (in shares) at Mar. 31, 2023	53,586	97,718				53,586	97,718

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Cash flows from operating activities:
Net loss	$ (18,132)	$ (334)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	16,942	12,906
Provision for subscription cancellations and non-renewals, net of deferred allowance	697	(279)
Amortization of deferred financing costs	63	53
Change in fair value of contingent consideration liability	200	700
Write-off of deferred financing costs		372
Stock-based compensation expense	11,434	4,933
Deferred income tax (benefit) expense	(12,984)	62
Non-cash operating lease costs	726	622
Other	(4)	412
Changes in operating assets and liabilities:
Accounts receivable	(795)	2,688
Prepaid expenses and other current assets	(2,109)	(1,091)
Deferred commissions	(459)	875
Accounts payable	3,065	1,555
Accrued expenses	17,578	3,806
Accrued and deferred compensation	(12,452)	(19,254)
Deferred revenue	4,352	(3,718)
Operating lease liabilities	(1,309)	(763)
Other	(58)	(950)
Net cash provided by operating activities	6,755	2,595
Cash flows from investing activities:
Acquisition of business, net of cash acquired		(474)
Property and equipment additions	(13,313)	(13,873)
Capitalized software additions	(4,007)	(2,912)
Purchase of investment securities, available-for-sale	(3,491)
Proceeds from maturities of investment securities, available-for-sale	3,250
Net cash used in investing activities	(17,561)	(17,259)
Cash flows from financing activities:
Net increase in customer funds obligations	10,989	1,046
Proceeds from term loan		50,000
Principal payments on long-term debt	(313)
Payments for deferred financing costs		(993)
Payments for taxes related to net share settlement of stock-based awards	(3,681)	(337)
Proceeds from exercise of stock options	1,490	600
Distributions under Tax Sharing Agreement		(536)
Payments of finance lease liabilities	(16)
Payments for deferred purchase commitments	(10,000)	(10,000)
Net cash (used in) provided by financing activities	(1,531)	39,780
Effect of exchange rate changes on cash, cash equivalents and restricted cash	204	(83)
Net (decrease) increase in cash, cash equivalents and restricted cash	(12,133)	25,033
Cash, cash equivalents and restricted cash, beginning of period	106,748	98,206
Cash, cash equivalents and restricted cash, end of period	$ 94,615	$ 123,239

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2023	Mar. 31, 2022
Reconciliation of cash, cash equivalents and restricted cash to the Condensed Consolidated Balance Sheets, end of period:
Cash and cash equivalents	$ 68,643	$ 97,340
Restricted cash-funds held for customers	25,972	25,899
Total cash, cash equivalents and restricted cash, end of period	$ 94,615	$ 123,239

SUMMARY OF SIGNIFICANT ACCOUNTI

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	3 Months Ended
	Mar. 31, 2023
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	1. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Nature of Business Vertex, Inc. (“Vertex”) and its consolidated subsidiaries and variable interest entities (“VIE”) (collectively, the “Company”) operate as solutions providers of state, local and value added tax calculation, compliance and analytics, offering software products which are sold through software license and software as a service (“cloud”) subscriptions. The Company also provides implementation and training services in connection with its software license and cloud subscriptions, transaction tax returns outsourcing, and other tax-related services. The Company sells to customers located throughout the United States of America (“U.S.”) and internationally. Basis of Consolidation The condensed consolidated financial statements are prepared in accordance with accounting principles generally accepted in the U.S. (“U.S. GAAP”) and include the accounts of the Company. All intercompany transactions have been eliminated in consolidation. The Company has a 65% controlling equity interest in Systax Sistemas Fiscais LTDA (“Systax”), a provider of Brazilian transaction tax content and software. Systax was determined to be a VIE and the accounts are included in the condensed consolidated condensed financial statements. Vertex does not have full decision-making authority over Systax; however, Vertex is the entity that most significantly participates in the variability of the fair value of Systax’s net assets and is considered the entity most closely associated to Systax. As such, Vertex is deemed the primary beneficiary of Systax and consolidates Systax into its condensed consolidated financial statements. Unaudited Interim Financial Information The accompanying unaudited interim condensed consolidated financial statements have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”) for interim financial information and include the accounts of the Company. Certain information and disclosures normally included in consolidated financial statements prepared in accordance with U.S. GAAP have been condensed or omitted. Accordingly, these interim condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and the related notes for the year ended December 31, 2022 included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2022 (the “2022 Annual Report”) filed with the SEC on March 10, 2023. The condensed consolidated balance sheet as of December 31, 2022 has been derived from audited financial statements included in the 2022 Annual Report. The accompanying interim condensed consolidated balance sheet as of March 31, 2023, the interim condensed consolidated statements of comprehensive loss for the three months ended March 31, 2023 and 2022, and the interim condensed consolidated statements of changes in stockholders’ equity and the interim condensed consolidated statements of cash flows for the three months ended March 31, 2023 and 2022 are unaudited. The unaudited interim condensed consolidated financial statements have been prepared on a basis consistent with that used to prepare the annual audited consolidated financial statements and include, in the opinion of management, all adjustments, consisting of normal and recurring items necessary for the fair presentation of the condensed consolidated financial statements. The operating results for the three months ended March 31, 2023 are not necessarily indicative of the results expected for the full year ending December 31, 2023. Segments The Company operates its business as one operating segment. For the three months ended March 31, 2023 and 2022, approximately 7% and 5%, respectively, of the Company’s revenues were generated from customers located outside the U.S. As of March 31, 2023 and December 31, 2022, $895 and $827, respectively, of the Company’s property and equipment assets were held outside the U.S. ​ Use of Estimates The preparation of condensed consolidated financial statements requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, equity, revenues and expenses during the reporting period. Significant estimates used in preparing these condensed consolidated financial statements include: (i) the estimated allowance for subscription cancellations, (ii) expected credit losses associated with the allowance for doubtful accounts; (iii) allowance for credit losses on available-for-sale debt securities; (iv) the reserve for self-insurance, (v) assumptions related to achievement of technological feasibility for software developed for sale, (vi) product life cycles, (vii) estimated useful lives and potential impairment of long-lived assets and intangible assets, (viii) potential impairment of goodwill, (ix) determination of the fair value of tangible and intangible assets acquired, liabilities assumed and consideration transferred in acquisitions, (x) amortization period of material rights and deferred commissions (xi) Black-Scholes-Merton option pricing model (“Black-Scholes model”) input assumptions used to determine the fair value of certain stock-based compensation awards and Employee Stock Purchase Plan (“ESPP”) purchase rights (xii) measurement of future purchase commitment, contingent consideration liabilities and deferred purchase consideration liabilities associated with acquisitions, and (xiii) the potential outcome of future tax consequences of events that have been recognized in the condensed consolidated financial statements or tax returns. Actual results may differ from these estimates. Supplemental Balance Sheet Disclosures Supplemental balance sheet disclosures are as follows for the respective periods: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, ​ ​ December 31, ​ 2023 ​ 2022 ​ (unaudited) ​ ​ ​ Prepaid expenses and other current assets: ​ ​ Prepaid expenses ​ $ 9,244 ​ $ 5,875 Prepaid insurance ​ ​ 1,469 ​ ​ 2,291 Prepaid licenses and support ​ ​ 11,823 ​ ​ 12,217 Prepaid expenses and other current assets ​ $ 22,536 ​ $ 20,383 ​ ​ ​ ​ ​ ​ ​ Accrued expenses: ​ ​ ​ ​ ​ ​ Accrued general expenses ​ $ 17,599 ​ $ 18,485 Accrued contract labor and professional fees ​ ​ 14,579 ​ ​ 17,421 Accrued income and other taxes ​ ​ 23,718 ​ ​ 2,328 Accrued expenses ​ $ 55,896 ​ $ 38,234 ​ ​ Recently Issued or Adopted Accounting Pronouncements As an “emerging growth company,” the Jumpstart Our Business Startups Act allows the Company to delay adoption of new or revised accounting pronouncements applicable to public companies until such pronouncements are made applicable to private companies. The Company has elected to delay adoption of certain new or revised accounting standards. As a result, the Company’s financial statements may not be comparable to the financial statements of issuers who are required to comply with the effective date for new or revised accounting standards that are applicable to public companies. Deferred Revenue In October 2021, the Financial Accounting Standard Board issued ASU No. 2021-08, Business Combinations (“ASU 2021-08”). ASU 2021-08 provides specific guidance on how to recognize and measure contract assets and contract liabilities related to revenue contracts with customers acquired in a business combination. This will align the accounting for these acquired contracts to the accounting for revenue contracts originated by the acquirer and will provide more comparable information to investors and other financial statement users seeking to better understand the financial impact of these acquisitions. The Company adopted this standard effective January 1, 2023 on a prospective basis for business combinations occurring on or after this date. Although this standard does not have a material impact on the Company’s current condensed consolidated financial statements, adoption could have a material impact on the accounting for future acquisitions reflected in the Company’s condensed consolidated financial statements.

REVENUE RECOGNITION

REVENUE RECOGNITION	3 Months Ended
	Mar. 31, 2023
REVENUE RECOGNITION
REVENUE RECOGNITION	2. REVENUE RECOGNITION Disaggregation of revenue The table reflects revenue by major source for the following periods: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended March 31, ​ ​ 2023 2022 ​ (unaudited) Software subscriptions: ​ ​ ​ ​ ​ Software licenses ​ $ 62,808 ​ $ 58,857 Cloud subscriptions ​ ​ 48,206 ​ ​ 38,274 Software subscriptions ​ ​ 111,014 ​ ​ 97,131 Services ​ 21,737 ​ 17,853 Total revenues ​ $ 132,751 ​ $ 114,984 ​ Contract balances Timing of revenue recognition may differ from the timing of invoicing customers. A receivable is recorded in the condensed consolidated balance sheets when customers are billed related to revenue to be collected and recognized for subscription agreements as there is an unconditional right to invoice and receive payment in the future related to these subscriptions. A receivable and related revenue may also be recorded in advance of billings to the extent services have been performed and the Company has a right under the contract to bill and collect for such performance. Subscription-based customers are generally invoiced annually at the beginning of each annual subscription period. Accounts receivable is presented net of an allowance for potentially uncollectible accounts and estimated cancellations of software license and cloud-based subscriptions (the “allowance”) of $10,641 and $9,554 at March 31, 2023 and December 31, 2022, respectively. The allowance for potentially uncollectible accounts represents future expected credit losses over the life of the receivables based on past experience, current information and forward-looking economic considerations. The beginning and ending balances of accounts receivable, net of allowance, are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the three months ended March 31, 2023 ​ For the year ended December 31, 2022 ​ ​ (unaudited) ​ ​ ​ Balance, beginning of period ​ $ 102,885 ​ $ 76,929 Balance, end of period ​ 102,760 ​ 102,885 Increase (decrease), net ​ $ (125) ​ $ 25,956 ​ A contract liability is recorded as deferred revenue on the condensed consolidated balance sheets when customers are billed in advance of performance obligations being satisfied, and revenue is recognized after invoicing ratably over the subscription period or over the amortization period of material rights. Deferred revenue is reflected net of a related deferred allowance for subscription cancellations (the “deferred allowance”) of $7,516 and $7,133 at March 31, 2023 and December 31, 2022, respectively. The deferred allowance represents the portion of the allowance for subscription cancellations associated with deferred revenue. The beginning and ending balances of and changes to the allowance and the deferred allowance are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the three months ended March 31, ​ ​ ​ 2023 ​ 2022 ​ ​ ​ Balance ​ Net Change Balance ​ Net Change ​ ​ ​ (unaudited) ​ Allowance balance, January 1, ​ $ (9,554) ​ ​ $ (9,151) ​ ​ Allowance balance, March 31, ​ (10,641) ​ ​ (8,450) ​ ​ Change in allowance ​ ​ ​ $ 1,087 ​ ​ ​ $ (701) ​ Deferred allowance balance, January 1, ​ 7,133 ​ ​ 6,537 ​ ​ Deferred allowance balance, March 31, ​ 7,516 ​ ​ 6,098 ​ ​ Change in deferred allowance ​ ​ ​ (383) ​ ​ ​ 439 ​ Net amount charged to revenues ​ ​ ​ $ 704 ​ ​ ​ $ (262) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The portion of deferred revenue expected to be recognized in revenue beyond one year is included in deferred revenue, net of current portion in the condensed consolidated balance sheets. The tables provide information about the balances of and changes to deferred revenue for the following periods: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of March 31, ​ As of December 31, ​ ​ 2023 ​ 2022 ​ (unaudited) ​ ​ Balances: ​ ​ Deferred revenue, current ​ $ 276,004 ​ $ 268,847 Deferred revenue, non-current ​ 7,112 ​ 10,289 Total deferred revenue ​ $ 283,116 ​ $ 279,136 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the three months ended March 31, ​ ​ 2023 ​ 2022 ​ ​ (unaudited) Changes to deferred revenue: ​ ​ Beginning balance ​ $ 279,136 ​ $ 249,010 Additional amounts deferred ​ 136,731 ​ 111,689 Revenues recognized ​ (132,751) ​ (114,984) Ending balance ​ $ 283,116 ​ $ 245,715 ​ ​ Contract costs Deferred sales commissions earned by the Company’s sales force and certain sales incentive programs and vendor referral agreements are considered incremental and recoverable costs of obtaining a contract with a customer. An asset is recognized for these incremental contract costs and reflected as deferred commissions in the condensed consolidated balance sheets. These contract costs are amortized on a straight-line basis over a period consistent with the transfer of the associated product and services to the customer, which is generally three years. Amortization of these costs are included in selling and marketing expense in the condensed consolidated statements of comprehensive loss. The Company periodically reviews these contract assets to determine whether events or changes in circumstances have occurred that could impact the period of benefit of these assets. There were no impairment losses recorded for the periods presented. ​ The changes to contract cost balances as of and for the following periods are: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the three months ended March 31, ​ ​ 2023 ​ 2022 ​ ​ (unaudited) Deferred commissions: ​ ​ Beginning balance ​ $ 15,463 ​ $ 12,555 Additions ​ 2,851 ​ 1,750 Amortization ​ (2,393) ​ (2,626) Ending balance ​ $ 15,921 ​ $ 11,679 ​

FINANCIAL INSTRUMENTS AND FAIR

FINANCIAL INSTRUMENTS AND FAIR VALUE MEASUREMENTS	3 Months Ended
	Mar. 31, 2023
FINANCIAL INSTRUMENTS AND FAIR VALUE MEASUREMENTS
FINANCIAL INSTRUMENTS AND FAIR VALUE MEASUREMENTS	3. FINANCIAL INSTRUMENTS AND FAIR VALUE MEASUREMENTS Assets and Liabilities Measured at Fair Value on a Recurring Basis The following table summarizes the Company’s fair value for its financial assets and liabilities measured at fair value on a recurring basis: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurements Using As of March 31, 2023 (unaudited) ​ Fair Value Prices in active markets for identical assets (Level 1) Significant other observable inputs (Level 2) Significant unobservable inputs (Level 3) Money Market Funds ​ $ 46,617 ​ $ 46,617 ​ $ — ​ $ — Commercial Paper ​ ​ 9,722 ​ ​ — ​ ​ 9,722 ​ ​ — U.S. Treasury Securities ​ ​ 5,338 ​ ​ — ​ ​ 5,338 ​ ​ — Tellutax Contingent Consideration ​ ​ 5,000 ​ ​ — ​ ​ — ​ ​ 5,000 Foreign Currency Forward Contracts ​ ​ 817 ​ ​ — ​ ​ 817 ​ ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurements Using As of December 31, 2022 ​ Fair Value Prices in active markets for identical assets (Level 1) Significant other observable inputs (Level 2) Significant unobservable inputs (Level 3) Money Market Funds ​ $ 67,430 ​ $ 67,430 ​ $ — ​ $ — Commercial Paper ​ ​ 9,660 ​ ​ — ​ ​ 9,660 ​ ​ — U.S. Treasury Securities ​ ​ 5,203 ​ ​ — ​ ​ 5,203 ​ ​ — Tellutax Contingent Consideration ​ ​ 4,800 ​ ​ — ​ ​ — ​ ​ 4,800 Foreign Currency Forward Contracts ​ ​ 569 ​ ​ — ​ ​ 569 ​ ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The Company has investments in high quality, short-term money market instruments which are issued and payable in U.S. dollars (“Money Market Funds”), which are included in cash and cash equivalents on the condensed consolidated balance sheets. Fair value inputs for these investments are considered Level 1 measurements within the fair value hierarchy since Money Market Fund fair values are known and observable through daily published floating net asset values. Securities classified as available-for-sale are reported at fair value using Level 2 inputs. The Company has investments in bank and corporate issued commercial paper (“Commercial Paper”), and U.S. treasury securities (“U.S. Treasury Securities”), the Company believes that Level 2 designation is appropriate under Accounting Standards Codification, (“ASC”) 820-10, Fair Value Measurements and Disclosures In connection with the January 2021 Tellutax LLC (“Tellutax”) acquisition, the sellers are entitled to contingent consideration if sales targets are met during a period of time following the acquisition (the “Tellutax Contingent Consideration”). The Tellutax Contingent Consideration is based on three potential earn-out payments determined by periodic revenue achievements over a thirty-month period. Such estimate represents a recurring fair value measurement with significant unobservable inputs, which management considers to be Level 3 measurements under the Fair Value Hierarchy. The significant assumptions used in these calculations included forecasted results and the estimated likelihood for each performance scenario. The fair value of Tellutax Contingent Consideration is estimated using a Monte Carlo Simulation to compute the expected cash flows from the payments specified in the purchase agreement. Such payments have no maximum limit, but if certain targets are not met, there will be no payment for the applicable measurement period. A fair value adjustment of $200 and $700 was recorded in other operating expense, net for the three months ended March 31, 2023 and 2022, respectively. At March 31, 2023, the Tellutax Contingent Consideration of $3,400 and $1,600 is included in purchase commitment and contingent consideration liabilities, current, and purchase commitment and contingent consideration liabilities, net of current portion, respectively, in the condensed consolidated balance sheets. At December 31, 2022, the Tellutax Contingent Consideration of $1,400 and $3,400 is included in purchase commitment and contingent consideration liabilities, current, and purchase commitment and contingent consideration liabilities, net of current portion, respectively, in the condensed consolidated balance sheets. Tellutax Contingent Consideration fair value as of March 31, 2023 and December 31, 2022 and unobservable inputs used for the Monte Carlo Simulation valuation were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, 2023 (unaudited) Liability Fair Value Valuation Technique Unobservable Inputs Tellutax Contingent Consideration ​ $ 5,000 ​ Monte Carlo Simulation ​ Revenue volatility ​ 70.0 % ​ ​ ​ ​ ​ ​ ​ Revenue discount rate ​ 22.1 % ​ ​ ​ ​ ​ ​ ​ Term (in years) ​ 2.1 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2022 Liability Fair Value Valuation Technique Unobservable Inputs Tellutax Contingent Consideration ​ $ 4,800 ​ Monte Carlo Simulation ​ Revenue volatility ​ 75.0 % ​ ​ ​ ​ ​ ​ ​ Revenue discount rate ​ 22.4 % ​ ​ ​ ​ ​ ​ ​ Term (in years) ​ 2.4 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Changes in the fair value of Tellutax Contingent Consideration during the three months ended March 31, 2023 were as follows: ​ ​ ​ ​ ​ ​ ​ Tellutax ​ ​ Contingent ​ ​ Consideration ​ ​ (unaudited) ​ ​ ​ Balance, January 1, 2023 ​ $ 4,800 Fair value adjustments ​ ​ 200 Balance, March 31, 2023 ​ $ 5,000 ​ ​ ​ ​ ​ Assets and Liabilities for Which Fair Value is Only Disclosed ​ The carrying amounts of cash and cash equivalents and the carrying amount of funds held for customers were the same as their respective fair values and are considered Level 1 measurements. The carrying amount of our bank debt approximates fair value as the variable rates on the debt approximate those commercially available in the market, and is considered a Level 3 measurement. Non-recurring Fair Value Measurements The LCR-Dixon Corporation (“LCR-Dixon”) acquisition on September 22, 2021, the acquisition of EVAT Solutions Limited (“EVAT”) and its wholly owned subsidiaries (collectively, “Taxamo”) on May 12, 2021, the Tellutax acquisition on January 25, 2021, and the Systax acquisition on January 10, 2020, were accounted for as business combinations and the total purchase price for each acquisition was allocated to the net assets acquired and liabilities assumed based on their estimated fair values. Deferred purchase consideration associated with the LCR-Dixon acquisition was $9,924 and $19,824 at March 31, 2023 and December 31, 2022, respectively. The Company has a contractual commitment to acquire the remaining equity interest from the original Systax quotaholders incrementally through 2024. Future purchase commitment payments for these incremental acquisition amounts are based on a multiple of Systax revenue and earnings before interest, depreciation, amortization and income taxes (“EBITDA”) performance at the end of 2022 and 2023, whereby the Company will have full ownership after the final transaction in 2024. Management determined these future purchase commitments to be a forward contract, resulting in the Company being required to estimate and record an estimated future purchase commitment amount (the “Purchase Commitment Liability”) in connection with recording the initial purchase. The fair value of the Purchase Commitment Liability at the acquisition date was finalized to be $12,592. This amount will fluctuate as a result of changes in foreign currency exchange rates and is reflected in purchase commitment and contingent consideration liabilities in the condensed consolidated balance sheets, with such changes in exchange rates being reflected in other comprehensive loss or income in the condensed consolidated statements of comprehensive loss. Adjustments to the settlement date value that arise as a result of remeasurement at future balance sheet dates will be recorded as interest expense related to financing costs in the condensed consolidated statements of comprehensive income (loss) in the period the change is identified. No such adjustments have been recorded for the three months ended March 31, 2023 or 2022. The Purchase Commitment Liability included in purchase commitment and contingent consideration liabilities, current and purchase commitment and contingent liabilities, net of current portion in the condensed consolidated balance sheet at March 31, 2023 was $4,940 and $5,213 respectively. The Purchase Commitment Liability included in purchase commitment and contingent consideration liabilities, current and purchase commitment and contingent consideration liabilities, net of current portion in the consolidated balance sheets on December 31, 2022 was $4,749 and $5,012, respectively. ​ The carrying amounts of both the LCR-Dixon deferred purchase consideration and the Systax Purchase Commitment Liability amounts discussed above approximated their respective fair values at such dates and are considered Level 3 non-recurring fair value measurements. ​ Derivative Instruments ​ The Company may periodically enter into derivative contracts to reduce our exposure to foreign currency exchange rates. Historically, the Company has not designated derivative contracts as hedges. Such derivative contracts are typically designed to manage specific risks according to our strategies, which may change from time to time. ​ The Company entered into a series of foreign currency forward contracts to reduce our exposure to adverse fluctuations in the Brazilian Real associated with a portion of the Systax Purchase Commitment Liability. Such forward contracts, have not been designated as a hedge, do not qualify for hedge accounting and are not material to our condensed consolidated financial statements. These forward contacts are remeasured at fair value on a recurring basis and are included in other assets in our condensed consolidated balance sheets with changes in their estimated fair value recognized as interest expense in our condensed consolidated statements of comprehensive loss. Our fair value determinations are based on foreign currency exchange rates in active markets, which are considered to be Level 2 measurements within the Fair Value Hierarchy.

PROPERTY AND EQUIPMENT

PROPERTY AND EQUIPMENT	3 Months Ended
	Mar. 31, 2023
PROPERTY AND EQUIPMENT
PROPERTY AND EQUIPMENT	4. PROPERTY AND EQUIPMENT The major components of property and equipment are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of March 31, ​ ​ As of December 31, ​ ​ 2023 ​ 2022 ​ (unaudited) ​ ​ ​ Leasehold improvements ​ $ 20,935 ​ $ 20,929 Equipment ​ 39,530 ​ 39,238 Computer software purchased ​ 11,903 ​ 11,892 Internal-use software developed: ​ ​ ​ ​ Cloud-based customer solutions ​ 149,851 ​ 142,980 Internal systems and tools ​ 47,846 ​ 42,035 Furniture and fixtures ​ 7,667 ​ 7,665 In-process internal-use software ​ 33,843 ​ 32,878 Property and equipment ​ 311,575 ​ 297,617 Less accumulated depreciation and amortization ​ (194,131) ​ (181,849) Property and equipment, net ​ $ 117,444 ​ $ 115,768 ​ Depreciation expense for property and equipment, excluding all internal-use software developed and finance leases, was $1,517 and $1,718 for the three months ended March 31, 2023 and 2022, respectively, and is reflected in depreciation and amortization in the condensed consolidated statements of comprehensive loss. Finance lease amortization was $279 and $235 for the three months ended March 31, 2023 and 2022, respectively, and is included in depreciation and amortization expense in the condensed consolidated statements of comprehensive loss. Assets under finance leases of $1,461 and $1,461, net of accumulated amortization of $1,140 and $861, respectively, at March 31, 2023 and December 31, 2022, respectively, are included in property and equipment in the condensed consolidated balance sheets. The major components of internal-use software are as follows: ​ ​ ​ ​ ​ ​ ​ ​ As of March 31, ​ As of December 31, ​ 2023 ​ 2022 ​ ​ (unaudited) ​ ​ ​ Internal-use software developed $ 197,697 ​ $ 185,015 Less accumulated depreciation (130,062) ​ (119,603) Internal-use software developed, net of accumulated depreciation 67,635 ​ 65,412 In-process internal-use software 33,843 ​ 32,878 Internal-use software developed, net $ 101,478 ​ $ 98,290 ​ Amounts included in property and equipment additions related to capitalized internal-use software on the condensed consolidated statements of cash flows are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the three months ended March 31, ​ ​ ​ 2023 ​ 2022 ​ ​ ​ (unaudited) ​ Cloud-based customer solutions $ 6,182 ​ $ 7,400 ​ Internal systems and tools ​ 6,858 ​ 4,848 ​ Total ​ $ 13,040 ​ $ 12,248 ​ ​ In-process internal-use software developed is not depreciated until it is available for its intended use. Depreciation expense for internal-use software developed for cloud-based customer solutions for the three months ended March 31, 2023 and 2022, was $8,148 and $6,331, respectively, and is included in cost of revenues, software subscriptions in the condensed consolidated statements of comprehensive loss. Depreciation expense for internal-use software developed for internal systems and tools for the three months ended March 31, 2023 and 2022 was $1,945 and $1,007, respectively, and is included in depreciation and amortization in the condensed consolidated statements of comprehensive loss.

CAPITALIZED SOFTWARE

CAPITALIZED SOFTWARE	3 Months Ended
	Mar. 31, 2023
CAPITALIZED SOFTWARE
CAPITALIZED SOFTWARE	5. CAPITALIZED SOFTWARE Capitalized software includes acquired software and direct labor and related expenses for software developed for sale for new products and enhancements to existing products. The major components of capitalized software are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of March 31, ​ As of December 31, ​ ​ 2023 ​ 2022 ​ ​ (unaudited) ​ ​ Capitalized software ​ $ 99,286 ​ $ 96,577 ​ Less accumulated amortization ​ (66,426) ​ (62,197) ​ Capitalized software, net of accumulated depreciation ​ 32,860 ​ 34,380 ​ In-process capitalized software ​ 5,930 ​ 4,632 ​ Capitalized software, net ​ $ 38,790 ​ $ 39,012 ​ ​ Software development costs capitalized for the three months ended March 31, 2023 and 2022, excluding acquisitions, were $4,007 and $2,912, respectively. Capitalized software amortization expense, including amortization of acquired technology, was $4,229 and $3,301 for the three months ended March 31, 2023 and 2022, respectively, and is included in cost of revenues, software subscriptions in the condensed consolidated statements of comprehensive loss.

GOODWILL AND OTHER INTANGIBLE A

GOODWILL AND OTHER INTANGIBLE ASSETS	3 Months Ended
	Mar. 31, 2023
GOODWILL AND OTHER INTANGIBLE ASSETS
GOODWILL AND OTHER INTANGIBLE ASSETS	6. GOODWILL AND OTHER INTANGIBLE ASSETS Goodwill and other intangible assets are as follows for the periods presented: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of March 31, ​ As of December 31, ​ ​ 2023 ​ 2022 ​ ​ (unaudited) ​ ​ ​ Goodwill ​ $ 254,897 ​ $ 251,842 Other intangible assets, net ​ ​ 4,406 ​ 5,181 Total ​ $ 259,303 ​ $ 257,023 ​ The Company has recognized various amortizable other intangible assets in connection with acquisitions related to customer relationships, technology, and tradenames. The following tables provide additional information for other intangible assets, which are individually not material to the condensed consolidated financial statements, for the periods presented: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of March 31, ​ ​ As of December 31, ​ ​ ​ ​ ​ ​ 2023 ​ 2022 ​ ​ ​ ​ ​ ​ (unaudited) ​ ​ ​ ​ Weighted average amortization period (years) ​ ​ ​ ​ ​ 3.5 ​ ​ 3.5 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gross value ​ ​ ​ ​ $ 10,802 ​ $ 10,667 ​ Accumulated amortization ​ ​ ​ ​ ​ (6,396) ​ ​ (5,486) ​ Carrying value ​ ​ ​ ​ $ 4,406 ​ $ 5,181 ​ The following table presents amortization of other intangible assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the three months ended March 31, ​ ​ ​ Cost of Revenues, Software Subscriptions ​ Selling and Marketing Expense ​ ​ Total Expense ​ 2023 ​ ​ ​ $ 58 $ 766 ​ $ 824 ​ 2022 ​ ​ ​ ​ ​ 65 ​ ​ 249 ​ ​ 314 ​

DEBT

DEBT	3 Months Ended
	Mar. 31, 2023
DEBT
DEBT	7. Credit Agreement On March 8, 2022, the Company entered into the Second Amendment to the Credit Agreement, with a banking syndicate, which provides (i) a term loan in the aggregate amount of $50,000 (the “Term Loan”); and (ii) a $200,000 revolving facility (the “Line of Credit”). Our indebtedness at March 31, 2023 and December 31, 2022 was as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ As of March 31, ​ ​ As of December 31, ​ ​ 2023 ​ ​ 2022 ​ ​ (unaudited) ​ ​ ​ ​ ​ ​ ​ ​ Term Loan $ 2,500 ​ $ 2,188 ​ 2,500 ​ ​ 2,188 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Term Loan ​ 46,250 ​ ​ 46,875 Deferred financing costs ​ (157) ​ ​ (166) Debt, net of current portion $ 46,093 ​ $ 46,709 Total debt, net of financing costs $ 48,593 ​ $ 48,897 ​ ​ ​ ​ ​ ​ ​

STOCKHOLDERS' EQUITY

STOCKHOLDERS' EQUITY	3 Months Ended
	Mar. 31, 2023
STOCKHOLDERS' EQUITY
STOCKHOLDERS' EQUITY	8. STOCKHOLDERS’ EQUITY Common Stock During the three months ended March 31, 2023 and 2022, the Company issued 592 and 272 shares of Class A common stock (“Class A”), respectively, related to the exercise of options, net of 17 and 47 shares, respectively, returned to the Company in lieu of payment of the exercise price and taxes due on these exercises. During the three months ended March 31, 2023 and 2022, the Company issued 391 and 3 shares of Class A common stock, respectively, in connection with the vesting of Restricted Stock Units (“RSUs”), net of 231 and 1 shares, respectively, returned to the Company in lieu of payment of taxes due on the vesting of these RSUs. During the three months ended March 31, 2023, a stockholder exchanged 2,589 shares of Class B common stock, for an equivalent number of shares of Class A common stock. Tax Sharing Agreement Payments In connection with termination of the Company’s S-Corporation election effective July 27, 2020, the Company entered into a tax sharing agreement (“Tax Sharing Agreement”) with the former S-Corporation shareholders. All obligations of the Company under the Tax Sharing Agreement are satisfied by adjustments of additional paid in capital. During the three months ended March 31, 2022, the Company distributed $536 to the former S-Corporation shareholders under the Tax Sharing Agreement to settle the Company’s obligation for income taxes related to the allocation of taxable income to the S-Corporation short tax period ended July 26, 2020.

EARNINGS PER SHARE

EARNINGS PER SHARE	3 Months Ended
	Mar. 31, 2023
EARNINGS PER SHARE
EARNINGS PER SHARE	9. EARNINGS PER SHARE The tables below illustrate the calculation of basic and diluted net loss per common share for the Class A common and Class B common for the periods reflected below. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the three months ended March 31, ​ Class A common stock: 2023 2022 ​ ​ ​ (unaudited) ​ Numerator, basic: ​ ​ ​ ​ ​ ​ Net loss attributable to all stockholders ​ $ (18,132) ​ $ (334) ​ Class A common stock as a percentage of total shares outstanding, basic ​ 33.49 % 28.39 % Net loss attributable to Class A stockholders, basic ​ $ (6,072) ​ $ (95) ​ ​ ​ ​ ​ ​ ​ ​ ​ Numerator, diluted: ​ ​ Net loss attributable to all stockholders ​ $ (18,132) ​ $ (334) ​ Class A common stock as a percentage of total shares outstanding, diluted ​ 33.49 % 28.39 % Net loss attributable to Class A stockholders, diluted ​ $ (6,072) ​ $ (95) ​ ​ ​ ​ ​ ​ ​ ​ ​ Denominator, basic and diluted: ​ ​ ​ Weighted average Class A common stock, basic ​ 50,456 ​ 42,349 ​ Dilutive effect of common stock equivalents (1) (2) ​ — ​ — ​ Weighted average Class A common stock, diluted ​ 50,456 ​ 42,349 ​ ​ ​ ​ ​ ​ ​ ​ ​ Net loss per Class A share, basic ​ $ (0.12) ​ $ (0.00) ​ Net loss per Class A share, diluted ​ $ (0.12) ​ $ (0.00) ​ (1) For the three months ended March 31, 2023, the following weighted-average outstanding shares of common stock equivalents by award type were excluded from the computation of diluted net loss per share attributable to Class A stockholders, as the impact of including them would have been anti-dilutive: 8,335 options (including 705 out-of-the-money options), 235 restricted stock awards (“RSA’s”), 3,141 RSU’s and 45 shares under the ESPP. (2) For the three months ended March 31, 2022, the following weighted-average outstanding shares of common stock equivalents by award type were excluded from the computation of diluted net loss per share attributable to Class A stockholders as the impact of including them would have been anti-dilutive: 9,430 options (including 768 out-of-themoney options), 326 RSA’s, 1,547 RSUs and 41 shares under the ESPP. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the three months ended March 31, ​ Class B common stock: 2023 2022 ​ ​ ​ (unaudited) ​ Numerator, basic: ​ ​ ​ ​ ​ ​ Net loss attributable to all stockholders ​ $ (18,132) ​ $ (334) ​ Class B common stock as a percentage of total shares outstanding, basic ​ 66.51 % 71.61 % Net loss attributable to Class B stockholders, basic ​ $ (12,060) ​ $ (239) ​ ​ ​ ​ ​ ​ ​ ​ ​ Numerator, diluted: ​ ​ Net loss attributable to all stockholders ​ $ (18,132) ​ $ (334) ​ Class B common stock as a percentage of total shares outstanding, diluted ​ 66.51 % 71.61 % Net loss attributable to Class B stockholders, diluted ​ $ (12,060) ​ $ (239) ​ ​ ​ ​ ​ ​ ​ ​ ​ Denominator, basic and diluted: ​ ​ ​ Weighted average Class B common stock, basic ​ 100,221 ​ 106,807 ​ Dilutive effect of common stock equivalents ​ — ​ — ​ Weighted average Class B common stock, diluted ​ 100,221 ​ 106,807 ​ ​ ​ ​ ​ ​ ​ ​ ​ Net loss per Class B share, basic ​ $ (0.12) ​ $ (0.00) ​ Net loss per Class B share, diluted ​ $ (0.12) ​ $ (0.00) ​ ​

STOCK-BASED AWARD PLANS

STOCK-BASED AWARD PLANS	3 Months Ended
	Mar. 31, 2023
STOCK-BASED AWARD PLANS
STOCK-BASED AWARD PLANS	10. STOCK-BASED AWARD PLANS The 2020 Plan provides the ability to grant cash and equity-based incentive awards to eligible employees, directors and service providers in order to attract, retain and motivate those that make important contributions to the Company. The Company issued stock options, RSAs, and RSUs under the 2020 Plan. As of March 31, 2023, 14,786 shares of Class A common were available for issuance under the 2020 Plan. Options The following table summarizes activity for options outstanding under the 2020 Plan for the three months ended March 31, 2023: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ Average ​ ​ ​ ​ ​ ​ ​ Average ​ Remaining ​ Aggregate ​ ​ ​ ​ ​ Exercise ​ Contractual ​ Intrinsic 2020 Plan Option Activity ​ Units ​ ​ Price ​ Life (Years) ​ Value ​ ​ ​ ​ ​ (unaudited) Outstanding at January 1, 2023 ​ 8,508 ​ $ 4.34 ​ 4.3 ​ $ 86,514 Exercised ​ (609) ​ $ 2.61 ​ ​ ​ ​ ​ 2020 Plan options outstanding at March 31, 2023 ​ 7,899 ​ $ 4.47 ​ 4.1 ​ ​ 128,086 2020 Plan options excercisable at March 31, 2023 5,983 ​ $ 3.30 3.3 ​ ​ 104,037 *Amended Options have indefinite contractual lives ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The detail of options outstanding, vested and exercisable under the 2020 Plan as of March 31, 2023 is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Options Outstanding ​ Options Vested and Exercisable ​ ​ Weighted ​ Weighted ​ ​ ​ ​ Average ​ ​ ​ Average Exercise Prices ​ Units ​ Life (Years) ​ Units ​ Life (Years) ​ ​ (unaudited) $0.15 to $0.71 1,656 ​ — ​ 1,656 ​ — $2.15 229 ​ 1.7 ​ 229 ​ 1.7 $2.50 2,126 ​ 3.3 ​ 2,126 ​ 3.3 $2.67 172 ​ 3.9 ​ 172 ​ 3.9 $3.17 836 ​ 5.1 ​ 491 ​ 4.9 $3.73 ​ 1,463 ​ 6.6 ​ 686 ​ 6.6 $4.70 ​ 658 ​ 6.9 ​ 316 ​ 6.9 $18.47 ​ 213 ​ 8.7 ​ 53 ​ 8.7 $18.96 ​ 235 ​ 8.4 ​ 105 ​ 8.4 $19.00 66 ​ 8.5 ​ 17 ​ 8.5 $32.16 245 ​ 7.9 ​ 132 ​ 7.5 ​ 7,899 ​ ​ 5,983 ​ ​ ​ The Board of Directors (“the Board”) intends all options granted to be exercisable at a price per share not less than the per share fair market value of the Company’s Class A common stock underlying the options on the date of grant. Compensation expense for option awards are measured based on the grant date fair value of the awards and recognized in the condensed consolidated statements of comprehensive loss over the period during which the participant is required to perform the requisite services. The vesting period is generally one There were no options issued under the 2020 Plan during the three months ended March 31, 2023 or 2022. ​ At March 31, 2023, $8,755 of unrecognized compensation expense associated with options is expected to be recognized over a weighted average period of approximately 1.8 years. ​ Restricted Stock Units The following table summarizes RSU activity for the three months ended March 31, 2023: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ ​ Average ​ ​ ​ ​ ​ Grant Date Fair ​ ​ ​ Units ​ Value Per Share ​ Outstanding at January 1, 2023 ​ 2,562 ​ $ 15.90 ​ Granted ​ 2,139 ​ ​ 15.41 ​ Vested ​ (622) ​ ​ 17.51 ​ Forfeited ​ (70) ​ ​ 14.82 ​ Outstanding at March 31, 2023 ​ 4,009 ​ $ 15.40 ​ ​ Stock-based compensation cost for RSUs is measured based on the fair value of the Company’s underlying common stock on the date of grant and is recognized on a straight-line basis in the condensed consolidated statements of comprehensive loss over the period during which the participant is required to perform services in exchange for the award, which is generally one In connection with the Taxamo acquisition, certain continuing employees of Taxamo received RSUs with service and performance conditions (“PSUs”). At March 31, 2023, there are 895 shares of our Class A common stock with an aggregate grant date fair value of $15,803 that will be accounted for as post-acquisition compensation expense over the vesting period if targets are achieved. The performance-based condition will be satisfied upon meeting certain performance targets for the year ended 2023. As of March 31, 2023, it is not probable that these targets will be met, thus no compensation expense has been recorded to date related to these PSUs. Restricted Stock Awards The following table summarizes RSA activity for the three months ended March 31, 2023: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ ​ Average ​ ​ ​ ​ ​ Grant Date Fair ​ ​ ​ Units ​ Value Per Share ​ Outstanding at January 1, 2023 ​ 235 ​ $ 14.91 ​ Outstanding at March 31, 2023 ​ 235 ​ $ 14.91 ​ ​ ​ ​ ​ ​ ​ ​ ​ Stock-based compensation cost for RSAs is measured based on the fair value of the Company’s underlying common stock on the date of grant and is recognized on a straight-line basis in the condensed consolidated statements of comprehensive loss over the period during which the participants are required to perform services in exchange for the award, which is generally one Employee Stock Purchase Plan The ESPP provides eligible employees with rights during each six-month ESPP offering period to purchase shares of the Company’s Class A common through payroll deductions of up to a specified percentage of their eligible compensation. The purchase price of the shares, in the absence of a contrary designation, is 85% of the lower of the fair value of the Class A common stock on the first or last day of the ESPP offering period. Amounts withheld from participants are reflected in accrued salaries and benefits in the condensed consolidated balance sheets until such shares are purchased. Amounts withheld from participants for the offering period ending May 31, 2023 aggregated $937 as of March 31, 2023. As of March 31, 2023, 5,065 shares of Class A common stock were available for issuance under the ESPP. As of March 31, 2023 there was approximately $131 of unrecognized ESPP stock-based compensation cost expected to be recognized on a straight-line basis over the remaining term of the six-month offering period ending May 31, 2023. ​ At March 31, 2023 and 2022, there were two ESPP offering periods open that end May 31, 2023 and 2022, respectively. The fair value of ESPP purchase rights for the offering periods is comprised of the value of the 15% ESPP discount and the value associated with the call or put over the respective ESPP offering period. ESPP offering periods reflected in the March 31, 2023 and 2022 financial statements include the periods noted below in the table. The value of the call or put was estimated using the Black-Scholes model with the following assumptions: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Offering Period Ending ​ 5/31/2023 ​ 11/30/2022 ​ 5/31/2022 ​ 11/30/2021 ​ Fair market value of common stock $ 17.21 ​ $ 11.16 ​ $ 17.38 ​ $ 19.89 ​ Volatility 46.4 % 35.4 % 37.3 % 35.1 % Expected term (years) 0.5 ​ 0.5 ​ 0.5 ​ 0.5 ​ Expected dividend yield - % - % - % - % Risk-free interest rate 4.7 % 1.6 % 0.1 % 0.1 % ​ Volatility is representative of expected stock price volatility over the offering period. Effective with the offering period beginning December 1, 2022, the Company’s volatility was applied and will be applied to future offering periods. Prior to this offering period, volatility was based on the historical and implied volatility of comparable publicly traded companies over a similar expected term for the respective offering periods. The expected term represents the term of the ESPP offering period, which is generally six months. The Company does not expect to pay dividends after the Offering. The risk-free interest rate was based on the rate for a U.S. Treasury zero-coupon issue with a term that closely approximates the expected term of the award at the date nearest the offering term. ​ Stock-Based Compensation ​ The Company recognized total stock-based compensation cost related to incentive awards, net of forfeitures, as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the three months ended March 31, ​ ​ 2023 2022 ​ ​ (unaudited) Stock-based compensation expense: ​ ​ ​ ​ ​ ​ Stock options ​ $ 2,171 ​ $ 2,281 RSUs ​ 8,345 ​ 1,779 RSAs ​ ​ 727 ​ ​ 734 ESPP ​ 191 ​ 139 Total stock-based compensation expense ​ $ 11,434 ​ $ 4,933 ​ ​ ​ ​ ​ ​ ​ ​ The Company recognized stock-based compensation cost in the condensed consolidated statements of comprehensive loss as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the three months ended March 31, ​ ​ 2023 2022 ​ ​ (unaudited) Stock-based compensation expense: ​ ​ ​ ​ ​ ​ Cost of revenues, software subscriptions ​ $ 996 ​ $ 446 Cost of revenues, services ​ 836 ​ 406 Research and development ​ 2,234 ​ 114 Selling and marketing ​ 2,898 ​ 1,572 General and administrative ​ 4,470 ​ 2,395 Total stock-based compensation expense ​ $ 11,434 ​ $ 4,933 ​

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	3 Months Ended
	Mar. 31, 2023
COMMITMENTS AND CONTINGENCIES
COMMITMENTS AND CONTINGENCIES	11. COMMITMENTS AND CONTINGENCIES In January 2022, the Company filed a complaint against a competitor alleging claims of unfair competition, intentional interference with contractual relations, and trade secret misappropriation. The outcome of the case is subject to a number of uncertainties, therefore the Company has not recognized any potential impact to the condensed consolidated financial statements. ​ The Company may become involved in various lawsuits and legal proceedings, which arise, in the ordinary course of business. However, litigation is subject to inherent uncertainties, and an adverse result in these or other matters may arise from time to time that may harm the Company’s business. The Company is not aware of any such legal proceedings or claims that management believes will have a material adverse effect on its business, financial condition, or operating results.

INCOME TAXES

INCOME TAXES	3 Months Ended
	Mar. 31, 2023
INCOME TAXES
INCOME TAXES	12. INCOME TAXES The Company reported income tax expense of $9,553 and $808 for the three months ended March 31, 2023, and 2022, respectively. The effective income tax rate ("ETR") was an expense of 111.4% for the three months ended March 31, 2023, compared to an expense of 170.5% for the three months ended March 31, 2022. The ETR for the three months ended March 31, 2023 and 2022 differ from the U.S. federal statutory income tax rate of 21% primarily due to income tax expense on income allocated to state jurisdictions, differences in tax rates on foreign jurisdiction income or loss, and limitations on deductions of certain employees’ compensation under Internal Revenue Code Section 162(m). In addition, the ETR for March 31, 2023 includes a valuation allowance recorded on certain foreign deferred tax assets.

SUMMARY OF SIGNIFICANT ACCOUN_2

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	3 Months Ended
	Mar. 31, 2023
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Nature of Business	Nature of Business Vertex, Inc. (“Vertex”) and its consolidated subsidiaries and variable interest entities (“VIE”) (collectively, the “Company”) operate as solutions providers of state, local and value added tax calculation, compliance and analytics, offering software products which are sold through software license and software as a service (“cloud”) subscriptions. The Company also provides implementation and training services in connection with its software license and cloud subscriptions, transaction tax returns outsourcing, and other tax-related services. The Company sells to customers located throughout the United States of America (“U.S.”) and internationally.
Basis of Consolidation	Basis of Consolidation The condensed consolidated financial statements are prepared in accordance with accounting principles generally accepted in the U.S. (“U.S. GAAP”) and include the accounts of the Company. All intercompany transactions have been eliminated in consolidation. The Company has a 65% controlling equity interest in Systax Sistemas Fiscais LTDA (“Systax”), a provider of Brazilian transaction tax content and software. Systax was determined to be a VIE and the accounts are included in the condensed consolidated condensed financial statements. Vertex does not have full decision-making authority over Systax; however, Vertex is the entity that most significantly participates in the variability of the fair value of Systax’s net assets and is considered the entity most closely associated to Systax. As such, Vertex is deemed the primary beneficiary of Systax and consolidates Systax into its condensed consolidated financial statements.
Unaudited Interim Financial Information	Unaudited Interim Financial Information The accompanying unaudited interim condensed consolidated financial statements have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”) for interim financial information and include the accounts of the Company. Certain information and disclosures normally included in consolidated financial statements prepared in accordance with U.S. GAAP have been condensed or omitted. Accordingly, these interim condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and the related notes for the year ended December 31, 2022 included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2022 (the “2022 Annual Report”) filed with the SEC on March 10, 2023. The condensed consolidated balance sheet as of December 31, 2022 has been derived from audited financial statements included in the 2022 Annual Report. The accompanying interim condensed consolidated balance sheet as of March 31, 2023, the interim condensed consolidated statements of comprehensive loss for the three months ended March 31, 2023 and 2022, and the interim condensed consolidated statements of changes in stockholders’ equity and the interim condensed consolidated statements of cash flows for the three months ended March 31, 2023 and 2022 are unaudited. The unaudited interim condensed consolidated financial statements have been prepared on a basis consistent with that used to prepare the annual audited consolidated financial statements and include, in the opinion of management, all adjustments, consisting of normal and recurring items necessary for the fair presentation of the condensed consolidated financial statements. The operating results for the three months ended March 31, 2023 are not necessarily indicative of the results expected for the full year ending December 31, 2023.
Segments	Segments The Company operates its business as one operating segment. For the three months ended March 31, 2023 and 2022, approximately 7% and 5%, respectively, of the Company’s revenues were generated from customers located outside the U.S. As of March 31, 2023 and December 31, 2022, $895 and $827, respectively, of the Company’s property and equipment assets were held outside the U.S. ​
Use of Estimates	Use of Estimates The preparation of condensed consolidated financial statements requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, equity, revenues and expenses during the reporting period. Significant estimates used in preparing these condensed consolidated financial statements include: (i) the estimated allowance for subscription cancellations, (ii) expected credit losses associated with the allowance for doubtful accounts; (iii) allowance for credit losses on available-for-sale debt securities; (iv) the reserve for self-insurance, (v) assumptions related to achievement of technological feasibility for software developed for sale, (vi) product life cycles, (vii) estimated useful lives and potential impairment of long-lived assets and intangible assets, (viii) potential impairment of goodwill, (ix) determination of the fair value of tangible and intangible assets acquired, liabilities assumed and consideration transferred in acquisitions, (x) amortization period of material rights and deferred commissions (xi) Black-Scholes-Merton option pricing model (“Black-Scholes model”) input assumptions used to determine the fair value of certain stock-based compensation awards and Employee Stock Purchase Plan (“ESPP”) purchase rights (xii) measurement of future purchase commitment, contingent consideration liabilities and deferred purchase consideration liabilities associated with acquisitions, and (xiii) the potential outcome of future tax consequences of events that have been recognized in the condensed consolidated financial statements or tax returns. Actual results may differ from these estimates.
Supplemental Balance Sheet Disclosures	Supplemental Balance Sheet Disclosures Supplemental balance sheet disclosures are as follows for the respective periods: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, ​ ​ December 31, ​ 2023 ​ 2022 ​ (unaudited) ​ ​ ​ Prepaid expenses and other current assets: ​ ​ Prepaid expenses ​ $ 9,244 ​ $ 5,875 Prepaid insurance ​ ​ 1,469 ​ ​ 2,291 Prepaid licenses and support ​ ​ 11,823 ​ ​ 12,217 Prepaid expenses and other current assets ​ $ 22,536 ​ $ 20,383 ​ ​ ​ ​ ​ ​ ​ Accrued expenses: ​ ​ ​ ​ ​ ​ Accrued general expenses ​ $ 17,599 ​ $ 18,485 Accrued contract labor and professional fees ​ ​ 14,579 ​ ​ 17,421 Accrued income and other taxes ​ ​ 23,718 ​ ​ 2,328 Accrued expenses ​ $ 55,896 ​ $ 38,234 ​
Recently Issued Accounting Pronouncements	Recently Issued or Adopted Accounting Pronouncements As an “emerging growth company,” the Jumpstart Our Business Startups Act allows the Company to delay adoption of new or revised accounting pronouncements applicable to public companies until such pronouncements are made applicable to private companies. The Company has elected to delay adoption of certain new or revised accounting standards. As a result, the Company’s financial statements may not be comparable to the financial statements of issuers who are required to comply with the effective date for new or revised accounting standards that are applicable to public companies. Deferred Revenue In October 2021, the Financial Accounting Standard Board issued ASU No. 2021-08, Business Combinations (“ASU 2021-08”). ASU 2021-08 provides specific guidance on how to recognize and measure contract assets and contract liabilities related to revenue contracts with customers acquired in a business combination. This will align the accounting for these acquired contracts to the accounting for revenue contracts originated by the acquirer and will provide more comparable information to investors and other financial statement users seeking to better understand the financial impact of these acquisitions. The Company adopted this standard effective January 1, 2023 on a prospective basis for business combinations occurring on or after this date. Although this standard does not have a material impact on the Company’s current condensed consolidated financial statements, adoption could have a material impact on the accounting for future acquisitions reflected in the Company’s condensed consolidated financial statements.

SUMMARY OF SIGNIFICANT ACCOUN_3

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)	3 Months Ended
	Mar. 31, 2023
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Schedule of supplemental balance sheet information	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, ​ ​ December 31, ​ 2023 ​ 2022 ​ (unaudited) ​ ​ ​ Prepaid expenses and other current assets: ​ ​ Prepaid expenses ​ $ 9,244 ​ $ 5,875 Prepaid insurance ​ ​ 1,469 ​ ​ 2,291 Prepaid licenses and support ​ ​ 11,823 ​ ​ 12,217 Prepaid expenses and other current assets ​ $ 22,536 ​ $ 20,383 ​ ​ ​ ​ ​ ​ ​ Accrued expenses: ​ ​ ​ ​ ​ ​ Accrued general expenses ​ $ 17,599 ​ $ 18,485 Accrued contract labor and professional fees ​ ​ 14,579 ​ ​ 17,421 Accrued income and other taxes ​ ​ 23,718 ​ ​ 2,328 Accrued expenses ​ $ 55,896 ​ $ 38,234 ​

REVENUE RECOGNITION (Tables)

REVENUE RECOGNITION (Tables)	3 Months Ended
	Mar. 31, 2023
REVENUE RECOGNITION
Schedule of disaggregation of revenue	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended March 31, ​ ​ 2023 2022 ​ (unaudited) Software subscriptions: ​ ​ ​ ​ ​ Software licenses ​ $ 62,808 ​ $ 58,857 Cloud subscriptions ​ ​ 48,206 ​ ​ 38,274 Software subscriptions ​ ​ 111,014 ​ ​ 97,131 Services ​ 21,737 ​ 17,853 Total revenues ​ $ 132,751 ​ $ 114,984 ​
Schedule of beginning and ending balances of accounts receivable, net of allowance	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the three months ended March 31, 2023 ​ For the year ended December 31, 2022 ​ ​ (unaudited) ​ ​ ​ Balance, beginning of period ​ $ 102,885 ​ $ 76,929 Balance, end of period ​ 102,760 ​ 102,885 Increase (decrease), net ​ $ (125) ​ $ 25,956 ​
Schedule of beginning and ending balances of and changes to the allowance and the deferred allowance	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the three months ended March 31, ​ ​ ​ 2023 ​ 2022 ​ ​ ​ Balance ​ Net Change Balance ​ Net Change ​ ​ ​ (unaudited) ​ Allowance balance, January 1, ​ $ (9,554) ​ ​ $ (9,151) ​ ​ Allowance balance, March 31, ​ (10,641) ​ ​ (8,450) ​ ​ Change in allowance ​ ​ ​ $ 1,087 ​ ​ ​ $ (701) ​ Deferred allowance balance, January 1, ​ 7,133 ​ ​ 6,537 ​ ​ Deferred allowance balance, March 31, ​ 7,516 ​ ​ 6,098 ​ ​ Change in deferred allowance ​ ​ ​ (383) ​ ​ ​ 439 ​ Net amount charged to revenues ​ ​ ​ $ 704 ​ ​ ​ $ (262) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Schedule of information about the balances of and changes to deferred revenue	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of March 31, ​ As of December 31, ​ ​ 2023 ​ 2022 ​ (unaudited) ​ ​ Balances: ​ ​ Deferred revenue, current ​ $ 276,004 ​ $ 268,847 Deferred revenue, non-current ​ 7,112 ​ 10,289 Total deferred revenue ​ $ 283,116 ​ $ 279,136 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the three months ended March 31, ​ ​ 2023 ​ 2022 ​ ​ (unaudited) Changes to deferred revenue: ​ ​ Beginning balance ​ $ 279,136 ​ $ 249,010 Additional amounts deferred ​ 136,731 ​ 111,689 Revenues recognized ​ (132,751) ​ (114,984) Ending balance ​ $ 283,116 ​ $ 245,715 ​
Schedule of information about the changes to contract cost balances	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the three months ended March 31, ​ ​ 2023 ​ 2022 ​ ​ (unaudited) Deferred commissions: ​ ​ Beginning balance ​ $ 15,463 ​ $ 12,555 Additions ​ 2,851 ​ 1,750 Amortization ​ (2,393) ​ (2,626) Ending balance ​ $ 15,921 ​ $ 11,679

FINANCIAL INSTRUMENTS AND FAI_2

FINANCIAL INSTRUMENTS AND FAIR VALUE MEASUREMENTS (Tables)	3 Months Ended
	Mar. 31, 2023
FINANCIAL INSTRUMENTS AND FAIR VALUE MEASUREMENTS
Schedule of assets and liabilities measured at fair value on a recurring basis	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurements Using As of March 31, 2023 (unaudited) ​ Fair Value Prices in active markets for identical assets (Level 1) Significant other observable inputs (Level 2) Significant unobservable inputs (Level 3) Money Market Funds ​ $ 46,617 ​ $ 46,617 ​ $ — ​ $ — Commercial Paper ​ ​ 9,722 ​ ​ — ​ ​ 9,722 ​ ​ — U.S. Treasury Securities ​ ​ 5,338 ​ ​ — ​ ​ 5,338 ​ ​ — Tellutax Contingent Consideration ​ ​ 5,000 ​ ​ — ​ ​ — ​ ​ 5,000 Foreign Currency Forward Contracts ​ ​ 817 ​ ​ — ​ ​ 817 ​ ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurements Using As of December 31, 2022 ​ Fair Value Prices in active markets for identical assets (Level 1) Significant other observable inputs (Level 2) Significant unobservable inputs (Level 3) Money Market Funds ​ $ 67,430 ​ $ 67,430 ​ $ — ​ $ — Commercial Paper ​ ​ 9,660 ​ ​ — ​ ​ 9,660 ​ ​ — U.S. Treasury Securities ​ ​ 5,203 ​ ​ — ​ ​ 5,203 ​ ​ — Tellutax Contingent Consideration ​ ​ 4,800 ​ ​ — ​ ​ — ​ ​ 4,800 Foreign Currency Forward Contracts ​ ​ 569 ​ ​ — ​ ​ 569 ​ ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Summary of estimated fair value of Tellutax contingent consideration	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, 2023 (unaudited) Liability Fair Value Valuation Technique Unobservable Inputs Tellutax Contingent Consideration ​ $ 5,000 ​ Monte Carlo Simulation ​ Revenue volatility ​ 70.0 % ​ ​ ​ ​ ​ ​ ​ Revenue discount rate ​ 22.1 % ​ ​ ​ ​ ​ ​ ​ Term (in years) ​ 2.1 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2022 Liability Fair Value Valuation Technique Unobservable Inputs Tellutax Contingent Consideration ​ $ 4,800 ​ Monte Carlo Simulation ​ Revenue volatility ​ 75.0 % ​ ​ ​ ​ ​ ​ ​ Revenue discount rate ​ 22.4 % ​ ​ ​ ​ ​ ​ ​ Term (in years) ​ 2.4 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Changes in fair value of Tellutax contingent consideration	​ ​ ​ ​ ​ ​ ​ Tellutax ​ ​ Contingent ​ ​ Consideration ​ ​ (unaudited) ​ ​ ​ Balance, January 1, 2023 ​ $ 4,800 Fair value adjustments ​ ​ 200 Balance, March 31, 2023 ​ $ 5,000 ​ ​ ​ ​ ​

PROPERTY AND EQUIPMENT (Tables)

PROPERTY AND EQUIPMENT (Tables)	3 Months Ended
	Mar. 31, 2023
PROPERTY AND EQUIPMENT
Schedule of major components of property and equipment	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of March 31, ​ ​ As of December 31, ​ ​ 2023 ​ 2022 ​ (unaudited) ​ ​ ​ Leasehold improvements ​ $ 20,935 ​ $ 20,929 Equipment ​ 39,530 ​ 39,238 Computer software purchased ​ 11,903 ​ 11,892 Internal-use software developed: ​ ​ ​ ​ Cloud-based customer solutions ​ 149,851 ​ 142,980 Internal systems and tools ​ 47,846 ​ 42,035 Furniture and fixtures ​ 7,667 ​ 7,665 In-process internal-use software ​ 33,843 ​ 32,878 Property and equipment ​ 311,575 ​ 297,617 Less accumulated depreciation and amortization ​ (194,131) ​ (181,849) Property and equipment, net ​ $ 117,444 ​ $ 115,768 ​
Schedule of major components of internal-use software	​ ​ ​ ​ ​ ​ ​ ​ As of March 31, ​ As of December 31, ​ 2023 ​ 2022 ​ ​ (unaudited) ​ ​ ​ Internal-use software developed $ 197,697 ​ $ 185,015 Less accumulated depreciation (130,062) ​ (119,603) Internal-use software developed, net of accumulated depreciation 67,635 ​ 65,412 In-process internal-use software 33,843 ​ 32,878 Internal-use software developed, net $ 101,478 ​ $ 98,290 ​
Schedule of amounts capitalized for internal-use software and included in property and equipment additions on the consolidated statements of cash flows	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the three months ended March 31, ​ ​ ​ 2023 ​ 2022 ​ ​ ​ (unaudited) ​ Cloud-based customer solutions $ 6,182 ​ $ 7,400 ​ Internal systems and tools ​ 6,858 ​ 4,848 ​ Total ​ $ 13,040 ​ $ 12,248 ​ ​

CAPITALIZED SOFTWARE (Tables)

CAPITALIZED SOFTWARE (Tables)	3 Months Ended
	Mar. 31, 2023
CAPITALIZED SOFTWARE
Schedule of major components of capitalized software	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of March 31, ​ As of December 31, ​ ​ 2023 ​ 2022 ​ ​ (unaudited) ​ ​ Capitalized software ​ $ 99,286 ​ $ 96,577 ​ Less accumulated amortization ​ (66,426) ​ (62,197) ​ Capitalized software, net of accumulated depreciation ​ 32,860 ​ 34,380 ​ In-process capitalized software ​ 5,930 ​ 4,632 ​ Capitalized software, net ​ $ 38,790 ​ $ 39,012 ​ ​

GOODWILL AND OTHER INTANGIBLE_2

GOODWILL AND OTHER INTANGIBLE ASSETS (Tables)	3 Months Ended
	Mar. 31, 2023
GOODWILL AND OTHER INTANGIBLE ASSETS
Changes in the carrying amount of goodwill	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of March 31, ​ As of December 31, ​ ​ 2023 ​ 2022 ​ ​ (unaudited) ​ ​ ​ Goodwill ​ $ 254,897 ​ $ 251,842 Other intangible assets, net ​ ​ 4,406 ​ 5,181 Total ​ $ 259,303 ​ $ 257,023 ​
Schedule of other acquired intangible assets	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of March 31, ​ ​ As of December 31, ​ ​ ​ ​ ​ ​ 2023 ​ 2022 ​ ​ ​ ​ ​ ​ (unaudited) ​ ​ ​ ​ Weighted average amortization period (years) ​ ​ ​ ​ ​ 3.5 ​ ​ 3.5 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gross value ​ ​ ​ ​ $ 10,802 ​ $ 10,667 ​ Accumulated amortization ​ ​ ​ ​ ​ (6,396) ​ ​ (5,486) ​ Carrying value ​ ​ ​ ​ $ 4,406 ​ $ 5,181 ​
Schedule of acquired intangible assets	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the three months ended March 31, ​ ​ ​ Cost of Revenues, Software Subscriptions ​ Selling and Marketing Expense ​ ​ Total Expense ​ 2023 ​ ​ ​ $ 58 $ 766 ​ $ 824 ​ 2022 ​ ​ ​ ​ ​ 65 ​ ​ 249 ​ ​ 314

DEBT (Tables)

DEBT (Tables)	3 Months Ended
	Mar. 31, 2023
DEBT
Schedule of Debt	​ ​ ​ ​ ​ ​ ​ ​ ​ As of March 31, ​ ​ As of December 31, ​ ​ 2023 ​ ​ 2022 ​ ​ (unaudited) ​ ​ ​ ​ ​ ​ ​ ​ Term Loan $ 2,500 ​ $ 2,188 ​ 2,500 ​ ​ 2,188 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Term Loan ​ 46,250 ​ ​ 46,875 Deferred financing costs ​ (157) ​ ​ (166) Debt, net of current portion $ 46,093 ​ $ 46,709 Total debt, net of financing costs $ 48,593 ​ $ 48,897 ​ ​ ​ ​ ​ ​

EARNINGS PER SHARE (Tables)

EARNINGS PER SHARE (Tables)	3 Months Ended
	Mar. 31, 2023
Class A
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Schedule of earnings per share basic and diluted	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the three months ended March 31, ​ Class A common stock: 2023 2022 ​ ​ ​ (unaudited) ​ Numerator, basic: ​ ​ ​ ​ ​ ​ Net loss attributable to all stockholders ​ $ (18,132) ​ $ (334) ​ Class A common stock as a percentage of total shares outstanding, basic ​ 33.49 % 28.39 % Net loss attributable to Class A stockholders, basic ​ $ (6,072) ​ $ (95) ​ ​ ​ ​ ​ ​ ​ ​ ​ Numerator, diluted: ​ ​ Net loss attributable to all stockholders ​ $ (18,132) ​ $ (334) ​ Class A common stock as a percentage of total shares outstanding, diluted ​ 33.49 % 28.39 % Net loss attributable to Class A stockholders, diluted ​ $ (6,072) ​ $ (95) ​ ​ ​ ​ ​ ​ ​ ​ ​ Denominator, basic and diluted: ​ ​ ​ Weighted average Class A common stock, basic ​ 50,456 ​ 42,349 ​ Dilutive effect of common stock equivalents (1) (2) ​ — ​ — ​ Weighted average Class A common stock, diluted ​ 50,456 ​ 42,349 ​ ​ ​ ​ ​ ​ ​ ​ ​ Net loss per Class A share, basic ​ $ (0.12) ​ $ (0.00) ​ Net loss per Class A share, diluted ​ $ (0.12) ​ $ (0.00) ​ (1) For the three months ended March 31, 2023, the following weighted-average outstanding shares of common stock equivalents by award type were excluded from the computation of diluted net loss per share attributable to Class A stockholders, as the impact of including them would have been anti-dilutive: 8,335 options (including 705 out-of-the-money options), 235 restricted stock awards (“RSA’s”), 3,141 RSU’s and 45 shares under the ESPP. (2) For the three months ended March 31, 2022, the following weighted-average outstanding shares of common stock equivalents by award type were excluded from the computation of diluted net loss per share attributable to Class A stockholders as the impact of including them would have been anti-dilutive: 9,430 options (including 768 out-of-themoney options), 326 RSA’s, 1,547 RSUs and 41 shares under the ESPP. ​
Class B
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Schedule of earnings per share basic and diluted	​

STOCK-BASED AWARD PLANS (Tables

STOCK-BASED AWARD PLANS (Tables)	3 Months Ended
	Mar. 31, 2023
Compensation plans:
Schedule of ESPP valuation assumptions	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Offering Period Ending ​ 5/31/2023 ​ 11/30/2022 ​ 5/31/2022 ​ 11/30/2021 ​ Fair market value of common stock $ 17.21 ​ $ 11.16 ​ $ 17.38 ​ $ 19.89 ​ Volatility 46.4 % 35.4 % 37.3 % 35.1 % Expected term (years) 0.5 ​ 0.5 ​ 0.5 ​ 0.5 ​ Expected dividend yield - % - % - % - % Risk-free interest rate 4.7 % 1.6 % 0.1 % 0.1 % ​
Schedule of stock-based compensation cost related to incentive awards	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the three months ended March 31, ​ ​ 2023 2022 ​ ​ (unaudited) Stock-based compensation expense: ​ ​ ​ ​ ​ ​ Stock options ​ $ 2,171 ​ $ 2,281 RSUs ​ 8,345 ​ 1,779 RSAs ​ ​ 727 ​ ​ 734 ESPP ​ 191 ​ 139 Total stock-based compensation expense ​ $ 11,434 ​ $ 4,933 ​ ​ ​ ​ ​ ​ ​ ​
Schedule of stock based compensation cost in consolidated statement of operations	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the three months ended March 31, ​ ​ 2023 2022 ​ ​ (unaudited) Stock-based compensation expense: ​ ​ ​ ​ ​ ​ Cost of revenues, software subscriptions ​ $ 996 ​ $ 446 Cost of revenues, services ​ 836 ​ 406 Research and development ​ 2,234 ​ 114 Selling and marketing ​ 2,898 ​ 1,572 General and administrative ​ 4,470 ​ 2,395 Total stock-based compensation expense ​ $ 11,434 ​ $ 4,933 ​
Stock options
Compensation plans:
Schedule of Option activity	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ Average ​ ​ ​ ​ ​ ​ ​ Average ​ Remaining ​ Aggregate ​ ​ ​ ​ ​ Exercise ​ Contractual ​ Intrinsic 2020 Plan Option Activity ​ Units ​ ​ Price ​ Life (Years) ​ Value ​ ​ ​ ​ ​ (unaudited) Outstanding at January 1, 2023 ​ 8,508 ​ $ 4.34 ​ 4.3 ​ $ 86,514 Exercised ​ (609) ​ $ 2.61 ​ ​ ​ ​ ​ 2020 Plan options outstanding at March 31, 2023 ​ 7,899 ​ $ 4.47 ​ 4.1 ​ ​ 128,086 2020 Plan options excercisable at March 31, 2023 5,983 ​ $ 3.30 3.3 ​ ​ 104,037 *Amended Options have indefinite contractual lives ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Schedule of outstanding, vested and exercisable	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Options Outstanding ​ Options Vested and Exercisable ​ ​ Weighted ​ Weighted ​ ​ ​ ​ Average ​ ​ ​ Average Exercise Prices ​ Units ​ Life (Years) ​ Units ​ Life (Years) ​ ​ (unaudited) $0.15 to $0.71 1,656 ​ — ​ 1,656 ​ — $2.15 229 ​ 1.7 ​ 229 ​ 1.7 $2.50 2,126 ​ 3.3 ​ 2,126 ​ 3.3 $2.67 172 ​ 3.9 ​ 172 ​ 3.9 $3.17 836 ​ 5.1 ​ 491 ​ 4.9 $3.73 ​ 1,463 ​ 6.6 ​ 686 ​ 6.6 $4.70 ​ 658 ​ 6.9 ​ 316 ​ 6.9 $18.47 ​ 213 ​ 8.7 ​ 53 ​ 8.7 $18.96 ​ 235 ​ 8.4 ​ 105 ​ 8.4 $19.00 66 ​ 8.5 ​ 17 ​ 8.5 $32.16 245 ​ 7.9 ​ 132 ​ 7.5 ​ 7,899 ​ ​ 5,983 ​ ​ ​
Restricted Stock Units
Compensation plans:
Schedule of Option activity	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ ​ Average ​ ​ ​ ​ ​ Grant Date Fair ​ ​ ​ Units ​ Value Per Share ​ Outstanding at January 1, 2023 ​ 2,562 ​ $ 15.90 ​ Granted ​ 2,139 ​ ​ 15.41 ​ Vested ​ (622) ​ ​ 17.51 ​ Forfeited ​ (70) ​ ​ 14.82 ​ Outstanding at March 31, 2023 ​ 4,009 ​ $ 15.40 ​ ​
Restricted Stock Awards
Compensation plans:
Schedule of restricted activity	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ ​ Average ​ ​ ​ ​ ​ Grant Date Fair ​ ​ ​ Units ​ Value Per Share ​ Outstanding at January 1, 2023 ​ 235 ​ $ 14.91 ​ Outstanding at March 31, 2023 ​ 235 ​ $ 14.91 ​ ​ ​ ​ ​ ​ ​ ​ ​

SUMMARY OF SIGNIFICANT ACCOUN_4

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) - segment	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Accounting policies:
Operating segments	1
Effective Income Tax Rate Reconciliation, Percent	111.40%	170.50%
Systax - VIE | Systax
Accounting policies:
Ownership (as a percent)	65%

SUMMARY OF SIGNIFICANT ACCOUN_5

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Concentration of Credit Risk (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Segment information:
Property and equipment	$ 117,444		$ 115,768
Outside United States
Segment information:
Property and equipment	$ 895		$ 827
Revenue | Geographic Concentration Risk | Outside United States
Segment information:
Risk percentage	7%	5%

SUMMARY OF SIGNIFICANT ACCOUN_6

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Supplemental Balance Sheet Information (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Prepaid expenses and other current assets:
Prepaid expenses	$ 9,244	$ 5,875
Prepaid Insurance	1,469	2,291
Prepaid licenses and support	11,823	12,217
Prepaid expenses and other current assets	22,536	20,383
Accrued expenses:
Accrued general expenses	17,599	18,485
Accrued contract labor and professional fees	14,579	17,421
Accrued income and other taxes	23,718	2,328
Accrued expenses	$ 55,896	$ 38,234

REVENUE RECOGNITION - Disaggreg

REVENUE RECOGNITION - Disaggregation of revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Disaggregation of revenue:
Total revenues	$ 132,751	$ 114,984
Software subscriptions
Disaggregation of revenue:
Total revenues	111,014	97,131
Software licenses
Disaggregation of revenue:
Total revenues	62,808	58,857
Cloud subscriptions
Disaggregation of revenue:
Total revenues	48,206	38,274
Services
Disaggregation of revenue:
Total revenues	$ 21,737	$ 17,853

REVENUE RECOGNITION - Accounts

REVENUE RECOGNITION - Accounts receivable, net (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022	Dec. 31, 2021
REVENUE RECOGNITION
Allowance for accounts receivable	$ 10,641	$ 9,554	$ 8,450	$ 9,151
Allowance for credit loss
Balance, beginning of period	102,885	76,929
Balance, end of period	102,760	102,885
Increase (decrease), net	$ (125)	$ 25,956

REVENUE RECOGNITION - Allowance

REVENUE RECOGNITION - Allowance and deferred allowance (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Allowance for credit loss
Beginning balance	$ (9,554)	$ (9,151)
Ending balance	(10,641)	(8,450)
Change in allowance	1,087	(701)
Deferred beginning balance	7,133	6,537
Deferred ending balance	7,516	6,098
Change in deferred allowance	(383)	439
Net amount charged to revenues	704	$ (262)
Software subscriptions
Allowance for credit loss
Beginning balance	(9,554)
Ending balance	(10,641)
Deferred beginning balance	7,133
Deferred ending balance	$ 7,516

REVENUE RECOGNITION - Deferred

REVENUE RECOGNITION - Deferred revenue (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022	Dec. 31, 2021
REVENUE RECOGNITION
Deferred revenue, current	$ 276,004	$ 268,847
Deferred revenue, non-current	7,112	10,289
Total deferred revenue	$ 283,116	$ 279,136	$ 245,715	$ 249,010

REVENUE RECOGNITION - Changes t

REVENUE RECOGNITION - Changes to deferred revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
REVENUE RECOGNITION
Beginning balance	$ 279,136	$ 249,010
Additional amounts deferred	136,731	111,689
Revenues recognized	(132,751)	(114,984)
Ending balance	$ 283,116	$ 245,715

REVENUE RECOGNITION - Contract

REVENUE RECOGNITION - Contract cost balances (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Deferred commissions:
Beginning balance	$ 15,463	$ 12,555
Additions	2,851	1,750
Amortization	(2,393)	(2,626)
Ending balance	$ 15,921	$ 11,679
Contract costs, amortization period	3 years
Impairment loss	$ 0

FINANCIAL INSTRUMENTS AND FAI_3

FINANCIAL INSTRUMENTS AND FAIR VALUE MEASUREMENTS (Details) $ in Thousands	1 Months Ended
	Jan. 31, 2021 USD ($) payment	Mar. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Fair Value, Recurring
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Forward foreign current contract, asset		$ 817	$ 569
Significant other observable inputs (Level 2) | Fair Value, Recurring
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Forward foreign current contract, asset		817	569
Money Market Funds | Fair Value, Recurring
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets, Fair Value Disclosure		46,617	67,430
Money Market Funds | Prices in active markets for identical assets (Level 1) | Fair Value, Recurring
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets, Fair Value Disclosure		46,617	67,430
Commercial Paper | Fair Value, Recurring
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets, Fair Value Disclosure		9,722	9,660
Commercial Paper | Significant other observable inputs (Level 2) | Fair Value, Recurring
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets, Fair Value Disclosure		9,722	9,660
U.S. Treasury Securities | Fair Value, Recurring
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets, Fair Value Disclosure		5,338	5,203
U.S. Treasury Securities | Significant other observable inputs (Level 2) | Fair Value, Recurring
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets, Fair Value Disclosure		5,338	5,203
Tellutax
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Tellutax Contingent Consideration		5,000	4,800
Number of potential earnout payments | payment	3
Revenue achievement period	30 months
Maximum limit on earnout payments	$ 0
Earn out payment for applicable measurement period	$ 0
Tellutax | Fair Value, Recurring
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Tellutax Contingent Consideration		5,000	4,800
Tellutax | Significant unobservable inputs (Level 3) | Fair Value, Recurring
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Tellutax Contingent Consideration		$ 5,000	$ 4,800

FINANCIAL INSTRUMENTS AND FAI_4

FINANCIAL INSTRUMENTS AND FAIR VALUE MEASUREMENTS - Estimated fair values of Tellutax contingent consideration (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2023 USD ($) Y	Mar. 31, 2022 USD ($)	Dec. 31, 2022 USD ($) Y
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value adjustments to contingent consideration	$ 200	$ 700
Purchase commitment and contingent consideration liabilities, current	8,340		$ 6,149
Purchase commitment and contingent consideration liabilities, net of current portion	6,813		8,412
Tellutax
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Tellutax Contingent Consideration	5,000		4,800
Fair value adjustments to contingent consideration	200	$ 700
Purchase commitment and contingent consideration liabilities, current	3,400		1,400
Purchase commitment and contingent consideration liabilities, net of current portion	$ 1,600		$ 3,400
Tellutax | Revenue volatility
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Contingent consideration measurement input	70		75
Tellutax | Revenue discount rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Contingent consideration measurement input	22.1		22.4
Tellutax | Term (in years)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Contingent consideration measurement input | Y	2.1		2.4

FINANCIAL INSTRUMENTS AND FAI_5

FINANCIAL INSTRUMENTS AND FAIR VALUE MEASUREMENTS - Changes in fair value of Tellutax contingent consideration (Details) - Contingent Consideration $ in Thousands	3 Months Ended
	Mar. 31, 2023 USD ($)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 4,800
Fair value adjustments	200
Ending balance	$ 5,000

FINANCIAL INSTRUMENTS AND FAI_6

FINANCIAL INSTRUMENTS AND FAIR VALUE MEASUREMENTS - Non-recurring Fair Value Measurements (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
LCR-Dixon
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deferred purchase consideration	$ 9,924		$ 19,824
Systax
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Purchase commitment liability	5,213		5,012
Purchase commitment liability	12,592
Adjustment due to currency exchange rates fluctuation	0	$ 0
Minimum Purchase Commitment liability	$ 4,940		$ 4,749

PROPERTY AND EQUIPMENT (Details

PROPERTY AND EQUIPMENT (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Property and equipment
Property and equipment	$ 311,575	$ 297,617
Less accumulated depreciation and amortization	(194,131)	(181,849)
Property and equipment, net	117,444	115,768
Leasehold improvements
Property and equipment
Property and equipment	20,935	20,929
Equipment
Property and equipment
Property and equipment	39,530	39,238
Computer software purchased
Property and equipment
Property and equipment	11,903	11,892
Internal-Use Software
Property and equipment
Property and equipment	197,697	185,015
Less accumulated depreciation and amortization	(130,062)	(119,603)
Property and equipment, net	101,478	98,290
Cloud-based customer solutions
Property and equipment
Property and equipment	149,851	142,980
Internal systems and tools
Property and equipment
Property and equipment	47,846	42,035
Furniture and fixtures
Property and equipment
Property and equipment	7,667	7,665
In-process internal-use software
Property and equipment
Property and equipment	$ 33,843	$ 32,878

PROPERTY AND EQUIPMENT - Additi

PROPERTY AND EQUIPMENT - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Property and equipment
Finance lease amortization	$ 279	$ 235
Property and equipment, gross	311,575		$ 297,617
Property and equipment	117,444		115,768
Accumulated amortization	194,131		181,849
Excluding internal-use software and capital leases
Property and equipment
Depreciation expense	1,517	1,718
Assets under finance leases
Property and equipment
Property and equipment, gross	1,461		1,461
Accumulated amortization	1,140		861
Internal-Use Software
Property and equipment
Property and equipment, gross	197,697		185,015
Property and equipment	101,478		98,290
Accumulated amortization	130,062		119,603
Depreciation expense	8,148	6,331
Internal systems and tools
Property and equipment
Property and equipment, gross	47,846		$ 42,035
Depreciation expense	$ 1,945	$ 1,007

PROPERTY AND EQUIPMENT - Major

PROPERTY AND EQUIPMENT - Major components of internal-use software (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Property and equipment
Property and equipment, gross	$ 311,575	$ 297,617
Less accumulated depreciation and amortization	(194,131)	(181,849)
Property and equipment	117,444	115,768
Internal-Use Software
Property and equipment
Property and equipment, gross	197,697	185,015
Less accumulated depreciation and amortization	(130,062)	(119,603)
Property and equipment, net excluding in-process internal-use software	67,635	65,412
Property and equipment	101,478	98,290
In-process internal-use software
Property and equipment
Property and equipment, gross	$ 33,843	$ 32,878

PROPERTY AND EQUIPMENT - Amount

PROPERTY AND EQUIPMENT - Amounts capitalized for internal-use software and included in property and equipment additions on the consolidated statements of cash flows (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Property and equipment
Capitalized internal-use software	$ 13,313	$ 13,873
Cloud-based customer solutions
Property and equipment
Capitalized internal-use software	6,182	7,400
Internal systems and tools
Property and equipment
Capitalized internal-use software	6,858	4,848
Internal-Use Software
Property and equipment
Capitalized internal-use software	$ 13,040	$ 12,248

CAPITALIZED SOFTWARE (Details)

CAPITALIZED SOFTWARE (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Capitalized software, movement
Capitalized software, net	$ 38,790		$ 39,012
Capitalized software amortization expense	4,229	$ 3,301
Software
Capitalized software, movement
Capitalized software, gross	99,286		96,577
Less accumulated amortization	(66,426)		(62,197)
Capitalized software, net	32,860		34,380
Capitalized development costs	4,007	$ 2,912
In-process internal-use software
Capitalized software, movement
Capitalized software, gross	$ 5,930		$ 4,632

GOODWILL AND OTHER INTANGIBLE_3

GOODWILL AND OTHER INTANGIBLE ASSETS (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Finite-Lived Intangible Assets [Line Items]
Goodwill.	$ 254,897	$ 251,842
Goodwill and other intangible assets	259,303	257,023
Other intangible assets
Finite-Lived Intangible Assets [Line Items]
Other intangible assets, net	$ 4,406	$ 5,181

GOODWILL AND OTHER INTANGIBLE_4

GOODWILL AND OTHER INTANGIBLE ASSETS - Intangibles (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Amortization of acquired intangible assets
Amortization	$ 824	$ 314
Cost of Revenues
Amortization of acquired intangible assets
Amortization	58	65
Selling and marketing
Amortization of acquired intangible assets
Amortization	$ 766	$ 249
Other intangible assets
Other intangible assets
Weighted Average Amortization Period (Years)	3 years 6 months		3 years 6 months
Gross Value	$ 10,802		$ 10,667
Accumulated amortization	(6,396)		(5,486)
Carrying Value	$ 4,406		$ 5,181

DEBT - Credit Agreement (Detail

DEBT - Credit Agreement (Details) $ in Thousands	Mar. 08, 2022 USD ($)
Line of Credit
Debt
Line of credit, capacity	$ 200,000
New Term Loan.
Debt
Face amount	$ 50,000

DEBT - Indebtness (Details)

DEBT - Indebtness (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Current portion of long-term debt
Current portion of long-term debt	$ 2,500	$ 2,188
Debt, net of current portion
Deferred financing costs	(157)	(166)
Total debt, net of current portion	46,093	46,709
Total Debt	48,593	48,897
Term Loan
Current portion of long-term debt
Current portion of long-term debt	2,500	2,188
Debt, net of current portion
Debt, net of current portion	$ 46,250	$ 46,875

STOCKHOLDERS EQUITY (Details)

STOCKHOLDERS EQUITY (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Common Stock
Exchange of shares	2,589
Class A
Common Stock
Exercise of stock options, net (in shares)	592	272
Shares exchanged in lieu	17	47
Class A | Restricted Stock Units
Common Stock
Shares issued upon vesting of Restricted Stock Units, net (in shares)	391	3
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation	231	1
S Corporation
Common Stock
Distributions		$ 536

EARNINGS PER SHARE (Details)

EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Numerator:
Net loss attributable to all stockholders	$ (18,132)	$ (334)
Class A
Numerator:
Common stock as a percentage of total shares outstanding, basic	33.49%	28.39%
Net loss attributable to stockholders, basic	$ (6,072)	$ (95)
Common stock as a percentage of total shares outstanding, diluted	33.49%	28.39%
Net loss attributable to stockholders, diluted	$ (6,072)	$ (95)
Denominator:
Weighted average common stock, basic (in shares)	50,456	42,349
Weighted average common stock, diluted (in shares)	50,456	42,349
Net loss per share, basic (in dollars per share)	$ (0.12)	$ 0
Net loss per share, diluted (in dollars per share)	$ (0.12)	$ 0
Class A | Amended Options
Denominator:
Anti-dilutive shares	8,335	9,430
Class A | Out-of-the-money options
Denominator:
Anti-dilutive shares	705	768
Class A | Restricted Stock Awards
Denominator:
Anti-dilutive shares	235	326
Class A | Restricted Stock Units
Denominator:
Anti-dilutive shares	3,141	1,547
Class A | ESPP
Denominator:
Anti-dilutive shares	45	41
Class B
Numerator:
Common stock as a percentage of total shares outstanding, basic	66.51%	71.61%
Net loss attributable to stockholders, basic	$ (12,060)	$ (239)
Common stock as a percentage of total shares outstanding, diluted	66.51%	71.61%
Net loss attributable to stockholders, diluted	$ (12,060)	$ (239)
Denominator:
Weighted average common stock, basic (in shares)	100,221	106,807
Weighted average common stock, diluted (in shares)	100,221	106,807
Net loss per share, basic (in dollars per share)	$ (0.12)	$ 0
Net loss per share, diluted (in dollars per share)	$ (0.12)	$ 0

STOCK-BASED AWARD PLANS - Optio

STOCK-BASED AWARD PLANS - Options under 2020 Plan (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Weighted Average Per Share
Compensation expense	$ 11,434	$ 4,933
Stock options
Units
Beginning, balance	8,508
Granted	0	0
Exercised	(609)
Ending balance	7,899		8,508
Exercisable	5,983
Weighted Average Per Share
Beginning balance	$ 4.34
Exercised	2.61
Ending Balance	4.47		$ 4.34
Exercisable	$ 3.30
Remaining contractual life, outstanding	4 years 1 month 6 days		4 years 3 months 18 days
Remaining contractual life, exercisable	3 years 3 months 18 days
Intrinsic value, outstanding	$ 128,086		$ 86,514
Intrinsic value, exercisable	104,037
Compensation expense	$ 2,171	$ 2,281
Unrecognized compensation expense period	1 year 9 months 18 days
Stock options | Minimum
Weighted Average Per Share
Vesting period	1 year
Stock options | Maximum
Weighted Average Per Share
Vesting period	4 years

STOCK-BASED AWARD PLANS - 2020

STOCK-BASED AWARD PLANS - 2020 Plan (Details) shares in Thousands	Mar. 31, 2023 shares
Stock options
Compensation plans:
Shares authorized	14,786

STOCK-BASED AWARD PLANS - Opt_2

STOCK-BASED AWARD PLANS - Options under 2020 Plan Price Range (Details) - Stock options	3 Months Ended
	Mar. 31, 2023 $ / shares shares
Options outstanding, vested and exercisable:
Options outstanding	7,899
Options outstanding, life	0 years
Options vested and exercisable	5,983
Options vested and exercisable, life	0 years
$0.15 to $0.71
Options outstanding, vested and exercisable:
Exercise prices, lower range | $ / shares	$ 0.15
Exercise prices, upper range | $ / shares	$ 0.71
Options outstanding	1,656,000
Options vested and exercisable	1,656,000
$2.15
Options outstanding, vested and exercisable:
Exercise prices | $ / shares	$ 2.15
Options outstanding	229,000
Options outstanding, life	1 year 8 months 12 days
Options vested and exercisable	229,000
Options vested and exercisable, life	1 year 8 months 12 days
$2.50
Options outstanding, vested and exercisable:
Exercise prices | $ / shares	$ 2.50
Options outstanding	2,126,000
Options outstanding, life	3 years 3 months 18 days
Options vested and exercisable	2,126,000
Options vested and exercisable, life	3 years 3 months 18 days
$2.67
Options outstanding, vested and exercisable:
Exercise prices | $ / shares	$ 2.67
Options outstanding	172,000
Options outstanding, life	3 years 10 months 24 days
Options vested and exercisable	172,000
Options vested and exercisable, life	3 years 10 months 24 days
$3.17
Options outstanding, vested and exercisable:
Exercise prices | $ / shares	$ 3.17
Options outstanding	836,000
Options outstanding, life	5 years 1 month 6 days
Options vested and exercisable	491,000
Options vested and exercisable, life	4 years 10 months 24 days
$3.73
Options outstanding, vested and exercisable:
Exercise prices | $ / shares	$ 3.73
Options outstanding	1,463,000
Options outstanding, life	6 years 7 months 6 days
Options vested and exercisable	686,000
Options vested and exercisable, life	6 years 7 months 6 days
$4.70
Options outstanding, vested and exercisable:
Exercise prices | $ / shares	$ 4.70
Options outstanding	658,000
Options outstanding, life	6 years 10 months 24 days
Options vested and exercisable	316,000
Options vested and exercisable, life	6 years 10 months 24 days
$18.47
Options outstanding, vested and exercisable:
Exercise prices | $ / shares	$ 18.47
Options outstanding	213,000
Options outstanding, life	8 years 8 months 12 days
Options vested and exercisable	53,000
Options vested and exercisable, life	8 years 8 months 12 days
$18.96
Options outstanding, vested and exercisable:
Exercise prices | $ / shares	$ 18.96
Options outstanding	235,000
Options outstanding, life	8 years 4 months 24 days
Options vested and exercisable	105,000
Options vested and exercisable, life	8 years 4 months 24 days
$19.00
Options outstanding, vested and exercisable:
Exercise prices | $ / shares	$ 19
Options outstanding	66,000
Options outstanding, life	8 years 6 months
Options vested and exercisable	17,000
Options vested and exercisable, life	8 years 6 months
$32.16
Options outstanding, vested and exercisable:
Exercise prices | $ / shares	$ 32.16
Options outstanding	245,000
Options outstanding, life	7 years 10 months 24 days
Options vested and exercisable	132,000
Options vested and exercisable, life	7 years 6 months

STOCK-BASED AWARD PLANS - Restr

STOCK-BASED AWARD PLANS - Restricted Stock Units (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Compensation plans:
Compensation expense	$ 11,434	$ 4,933
Unrecognized compensation cost	8,755
Restricted Stock Units
Compensation plans:
Compensation expense	8,345	$ 1,779
Unrecognized compensation cost	$ 53,653
Unrecognized compensation expense period	3 years 3 months 18 days
Units
Beginning balance (in units)	2,562
Granted (in units)	2,139
Vested (in units)	(622)
Forfeited (in units)	(70)
Ending balance (in units)	4,009
Weighted Average Per Share
Beginning balance (in dollars per share)	$ 15.90
Granted (in dollars per share)	15.41
Vested (in dollars per share)	17.51
Forfeited (in dollars per share)	14.82
Ending balance (in dollars per share)	$ 15.40
Restricted Stock Units | Minimum
Compensation plans:
Service requirement (in years)	1 year
Restricted Stock Units | Maximum
Compensation plans:
Service requirement (in years)	4 years
PSU | Taxamo
Compensation plans:
Compensation expense	$ 0
Grant date fair value	$ 15,803
Units
Granted (in units)	895

STOCK-BASED AWARD PLANS - Res_2

STOCK-BASED AWARD PLANS - Restricted Stock Awards (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Weighted Average Per Share
Compensation expense	$ 11,434	$ 4,933
Unrecognized compensation cost	$ 8,755
Restricted Stock Awards
Units
Beginning balance (in units)	235
Ending balance (in units)	235
Weighted Average Per Share
Beginning balance (in dollars per share)	$ 14.91
Ending balance (in dollars per share)	$ 14.91
Compensation expense	$ 727	$ 734
Unrecognized compensation cost	$ 1,389
Unrecognized compensation expense period	9 months 18 days
Restricted Stock Awards | Minimum
Compensation plans:
Service requirement (in years)	1 year
Restricted Stock Awards | Maximum
Compensation plans:
Service requirement (in years)	4 years

STOCK-BASED AWARD PLANS - Emplo

STOCK-BASED AWARD PLANS - Employee Stock Purchase Plan (Details) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2023 USD ($) period shares	Mar. 31, 2022 period
Compensation plans:
Unrecognized compensation cost	$ 8,755
Class A
Compensation plans:
Purchase price as a percent of fair value	85%
ESPP
Compensation plans:
Reserved for issuance | shares	5,065
Amounts withheld from participants	$ 937
Unrecognized compensation cost	$ 131
Number of offering periods | period	2	2
ESPP offering period	6 months
Discount	15%

STOCK-BASED AWARD PLANS - ESPP

STOCK-BASED AWARD PLANS - ESPP - Option-pricing model key input assumptions (Details) - Initial Public Offering - ESPP - $ / shares	1 Months Ended
	May 31, 2023	Nov. 30, 2022	May 31, 2022	Nov. 30, 2021
Fair Value Assumptions and Methodology
Fair market value of common stock	$ 17.21	$ 11.16	$ 17.38	$ 19.89
Volatility	46.40%	35.40%	37.30%	35.10%
Expected term (in years)	6 months	6 months	6 months	6 months
Risk-free interest rate	4.70%	1.60%	0.10%	0.10%

STOCK-BASED AWARD PLANS - Stock

STOCK-BASED AWARD PLANS - Stock based compensation (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Allocation of costs
Compensation expense	$ 11,434	$ 4,933
Stock options
Allocation of costs
Compensation expense	2,171	2,281
Restricted Stock Units
Allocation of costs
Compensation expense	8,345	1,779
Restricted Stock Awards
Allocation of costs
Compensation expense	727	734
ESPP
Allocation of costs
Compensation expense	$ 191	$ 139

STOCK-BASED AWARD PLANS - Sto_2

STOCK-BASED AWARD PLANS - Stock based compensation, comprehensive loss (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Allocation of costs
Compensation expense	$ 11,434	$ 4,933
Research and development
Allocation of costs
Compensation expense	2,234	114
Selling and marketing
Allocation of costs
Compensation expense	2,898	1,572
General and administrative
Allocation of costs
Compensation expense	4,470	2,395
Software subscriptions
Allocation of costs
Compensation expense	996	446
Services
Allocation of costs
Compensation expense	$ 836	$ 406

INCOME TAXES - (Details)

INCOME TAXES - (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
INCOME TAXES
Income tax expense	$ 9,553	$ 808
Effective tax rate (as a percent)	111.40%	170.50%
U.S. federal statutory income tax rate	21%	21%