00100 - Statement - Condensed Consolidated Balance Sheets link:presentationLink link:calculationLink link:definitionLink 00200 - Statement - Condensed Consolidated Statements of Comprehensive Loss link:presentationLink link:calculationLink link:definitionLink 00400 - Statement - Condensed Consolidated Statements of Cash Flows link:presentationLink link:calculationLink link:definitionLink 00405 - Statement - Condensed Consolidated Statements of Cash Flows (Parenthetical) link:presentationLink link:calculationLink link:definitionLink 40204 - Disclosure - REVENUE RECOGNITION - Deferred revenue (Details) link:presentationLink link:calculationLink link:definitionLink 40301 - Disclosure - BUSINESS COMBINATIONS (Details) link:presentationLink link:calculationLink link:definitionLink 40302 - Disclosure - BUSINESS COMBINATIONS - Net assets and liabilities (Details) link:presentationLink link:calculationLink link:definitionLink 40501 - Disclosure - PROPERTY AND EQUIPMENT (Details) link:presentationLink link:calculationLink link:definitionLink 40503 - Disclosure - PROPERTY AND EQUIPMENT - Major components of internal-use software (Details) link:presentationLink link:calculationLink link:definitionLink 40702 - Disclosure - LEASES - Lease Assets and Liabilities (Details) link:presentationLink link:calculationLink link:definitionLink 40703 - Disclosure - LEASES - Lease Costs, Weighted Average Term and Rates (Details) link:presentationLink link:calculationLink link:definitionLink 40704 - Disclosure - LEASES - Future Maturity of Lease Liabilities (Details) link:presentationLink link:calculationLink link:definitionLink 40704 - Disclosure - LEASES - Future Maturity of Lease Liabilities (Details) (Calc 2) link:presentationLink link:calculationLink link:definitionLink 40705 - Disclosure - LEASES - Future Maturity of Lease Liabilities under ASU 840 (Details) link:presentationLink link:calculationLink link:definitionLink 40801 - Disclosure - GOODWILL AND OTHER INTANGIBLE ASSETS (Details) link:presentationLink link:calculationLink link:definitionLink 00090 - Document - Document and Entity Information link:presentationLink link:calculationLink link:definitionLink 00105 - Statement - Condensed Consolidated Balance Sheets (Parenthetical) link:presentationLink link:calculationLink link:definitionLink 00300 - Statement - Condensed Consolidated Statements of Changes in Equity (Deficit) link:presentationLink link:calculationLink link:definitionLink 30303 - Disclosure - BUSINESS COMBINATIONS (Tables) link:presentationLink link:calculationLink link:definitionLink 30603 - Disclosure - CAPITALIZED SOFTWARE (Tables) link:presentationLink link:calculationLink link:definitionLink 31103 - Disclosure - EARNINGS PER SHARE (Tables) link:presentationLink link:calculationLink link:definitionLink 31203 - Disclosure - STOCK-BASED AWARD PLANS (Tables) link:presentationLink link:calculationLink link:definitionLink 40101 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Basis of Consolidation (Details) link:presentationLink link:calculationLink link:definitionLink 40102 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Segments (Details) link:presentationLink link:calculationLink link:definitionLink 40103 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Useful life (Details) link:presentationLink link:calculationLink link:definitionLink 40104 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Stock-Based Compensation (Details) link:presentationLink link:calculationLink link:definitionLink 40105 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Revenue Recognition (Details) link:presentationLink link:calculationLink link:definitionLink 40105 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Revenue Recognition Default (Details) link:presentationLink link:calculationLink link:definitionLink 40107 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Recently Issued Accounting Pronouncements (Details) link:presentationLink link:calculationLink link:definitionLink 40201 - Disclosure - REVENUE RECOGNITION - Disaggregation of revenue (Details) link:presentationLink link:calculationLink link:definitionLink 40202 - Disclosure - REVENUE RECOGNITION - Accounts receivable, net (Details) link:presentationLink link:calculationLink link:definitionLink 40303 - Disclosure - BUSINESS COMBINATIONS - Intangible assets acquired in the acquisition (Details) link:presentationLink link:calculationLink link:definitionLink 40401 - Disclosure - FINANCIAL INSTRUMENTS AND FAIR VALUE MEASUREMENTS (Details) link:presentationLink link:calculationLink link:definitionLink 40402 - Disclosure - FINANCIAL INSTRUMENTS AND FAIR VALUE MEASUREMENTS - Estimated fair values of Tellutax contingent consideration (Details) link:presentationLink link:calculationLink link:definitionLink 40403 - Disclosure - FINANCIAL INSTRUMENTS AND FAIR VALUE - Changes in fair value of Tellutax contingent consideration (Details) link:presentationLink link:calculationLink link:definitionLink 40502 - Disclosure - PROPERTY AND EQUIPMENT - Additional Information (Details) link:presentationLink link:calculationLink link:definitionLink 40504 - Disclosure - PROPERTY AND EQUIPMENT - Amounts capitalized for internal-use software and included in property and equipment additions on the consolidated statements of cash flows (Details) link:presentationLink link:calculationLink link:definitionLink 40601 - Disclosure - CAPITALIZED SOFTWARE (Details) link:presentationLink link:calculationLink link:definitionLink 40701 - Disclosure - LEASES (Details) link:presentationLink link:calculationLink link:definitionLink 40802 - Disclosure - GOODWILL AND OTHER INTANGIBLE ASSETS - Changes (Details) link:presentationLink link:calculationLink link:definitionLink 40803 - Disclosure - GOODWILL AND OTHER INTANGIBLE ASSETS - Intangibles (Details) link:presentationLink link:calculationLink link:definitionLink 40901 - Disclosure - DEBT - Credit Agreement (Details) link:presentationLink link:calculationLink link:definitionLink 41001 - Disclosure - STOCKHOLDERS EQUITY (Details) link:presentationLink link:calculationLink link:definitionLink 41101 - Disclosure - EARNINGS PER SHARE (Details) link:presentationLink link:calculationLink link:definitionLink 41201 - Disclosure - STOCK-BASED AWARD PLANS - Stock-Based Award Plans (Details) link:presentationLink link:calculationLink link:definitionLink 41202 - Disclosure - STOCK-BASED AWARD PLANS - 2020 Plan (Details) link:presentationLink link:calculationLink link:definitionLink 41203 - Disclosure - STOCK-BASED AWARD PLANS - Amended Options (Details) link:presentationLink link:calculationLink link:definitionLink 41204 - Disclosure - STOCK-BASED AWARD PLANS - Options under 2020 Plan (Details) link:presentationLink link:calculationLink link:definitionLink 41205 - Disclosure - STOCK-BASED AWARD PLANS - Options under 2020 Plan Price Range (Details) link:presentationLink link:calculationLink link:definitionLink 41206 - Disclosure - STOCK-BASED AWARD PLANS - Options under 2020 Plan Options issued (Details) link:presentationLink link:calculationLink link:definitionLink 41207 - Disclosure - STOCK-BASED AWARD PLANS - Restricted Stock Units (Details) link:presentationLink link:calculationLink link:definitionLink 41208 - Disclosure - STOCK-BASED AWARD PLANS - Restricted Stock Awards (Details) link:presentationLink link:calculationLink link:definitionLink 41209 - Disclosure - STOCK-BASED AWARD PLANS - Employee Stock Purchase Plan (Details) link:presentationLink link:calculationLink link:definitionLink 41210 - Disclosure - STOCK-BASED AWARD PLANS - ESPP - Option-pricing model key input assumptions (Details) link:presentationLink link:calculationLink link:definitionLink 41211 - Disclosure - STOCK-BASED AWARD PLANS - Stock based compensation (Details) link:presentationLink link:calculationLink link:definitionLink 41212 - Disclosure - STOCK-BASED AWARD PLANS - Stock based compensation, comprehensive income (Details) link:presentationLink link:calculationLink link:definitionLink 10101 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES link:presentationLink link:calculationLink link:definitionLink 10201 - Disclosure - REVENUE RECOGNITION link:presentationLink link:calculationLink link:definitionLink 10301 - Disclosure - BUSINESS COMBINATIONS link:presentationLink link:calculationLink link:definitionLink 10401 - Disclosure - FINANCIAL INSTRUMENTS AND FAIR VALUE MEASUREMENTS link:presentationLink link:calculationLink link:definitionLink 10501 - Disclosure - PROPERTY AND EQUIPMENT link:presentationLink link:calculationLink link:definitionLink 10601 - Disclosure - CAPITALIZED SOFTWARE link:presentationLink link:calculationLink link:definitionLink 10701 - Disclosure - LEASES link:presentationLink link:calculationLink link:definitionLink 10801 - Disclosure - GOODWILL AND OTHER INTANGIBLE ASSETS link:presentationLink link:calculationLink link:definitionLink 10901 - Disclosure - DEBT link:presentationLink link:calculationLink link:definitionLink 11001 - Disclosure - STOCKHOLDERS' EQUITY link:presentationLink link:calculationLink link:definitionLink 11101 - Disclosure - EARNINGS PER SHARE link:presentationLink link:calculationLink link:definitionLink 11201 - Disclosure - STOCK-BASED AWARD PLANS link:presentationLink link:calculationLink link:definitionLink 11301 - Disclosure - LEGAL PROCEEDINGS link:presentationLink link:calculationLink link:definitionLink 20102 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies) link:presentationLink link:calculationLink link:definitionLink 30103 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables) link:presentationLink link:calculationLink link:definitionLink 30203 - Disclosure - REVENUE RECOGNITION (Tables) link:presentationLink link:calculationLink link:definitionLink 30403 - Disclosure - FINANCIAL INSTRUMENTS AND FAIR VALUE MEASUREMENTS (Tables) link:presentationLink link:calculationLink link:definitionLink 30503 - Disclosure - PROPERTY AND EQUIPMENT (Tables) link:presentationLink link:calculationLink link:definitionLink 30703 - Disclosure - LEASES (Tables) link:presentationLink link:calculationLink link:definitionLink 30803 - Disclosure - GOODWILL AND OTHER INTANGIBLE ASSETS (Tables) link:presentationLink link:calculationLink link:definitionLink 40106 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Supplemental Cash Flow Disclosures (Details) link:presentationLink link:calculationLink link:definitionLink 40203 - Disclosure - REVENUE RECOGNITION - Allowance and deferred allowance (Details) link:presentationLink link:calculationLink link:definitionLink 40205 - Disclosure - REVENUE RECOGNITION - Changes to deferred revenue (Details) link:presentationLink link:calculationLink link:definitionLink 40206 - Disclosure - REVENUE RECOGNITION - Contract cost balances (Details) link:presentationLink link:calculationLink link:definitionLink