Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Cash flows from operating activities:
Net (loss) income	$ (979)	$ 563	$ (4,961)
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Depreciation and amortization	18,217	16,564	11,839
Equity-based compensation	10,452	6,124	1,567
Provision for doubtful accounts	177	30	14
Amortization of debt discount and issuance costs	3,703	721	1,072
Debt issuance cost write offs	141	152	0
Loss on repurchase of exchangeable notes	2,297	0	0
Amortization of capitalized client acquisition costs	398	0	0
Loss on disposal of assets	1	8	5
Benefit from deferred income taxes	(3,207)	(586)	(682)
Non-cash change in fair value of warrant liability	0	0	8,487
(Decrease) increase in non-cash contingent consideration expense from original estimate	(1,409)	3,389	3,866
Changes in operating assets:
Accounts receivable	(1,028)	2,430	(2,321)
Prepaid expenses and other current assets	(984)	(817)	1,017
Other assets	(1,544)	(2,769)	(3,182)
Changes in operating liabilities:
Accounts payable	239	(1,768)	1,172
Accrued expenses and other current liabilities	1,575	1,572	2,040
Deferred revenue	617	2,588	(123)
Other long-term liabilities	93	(44)	362
Contingent consideration paid in excess of original estimates	(5,039)	(1,560)	(2,092)
Net cash provided by operating activities	23,720	26,597	18,080
Cash flows from investing activities:
Expenditures for property and equipment	(2,911)	(807)	(2,217)
Expenditures for capitalized software	(2,893)	(2,227)	(1,092)
Purchases of merchant portfolios and residual buyouts	(1,788)	(3,586)	(1,207)
Acquisitions of businesses, net of cash acquired	(27,689)	(137,036)	(32,362)
Acquisition of other intangibles	(150)	(72)	(1,177)
Net cash used in investing activities	(35,431)	(143,728)	(38,055)
Cash flows from financing activities:
Proceeds from revolving credit facility	172,123	188,491	27,250
Payments of revolving credit facility	(313,267)	(51,867)	(95,600)
Proceeds from borrowings on exchangeable notes	138,000	0	0
Payments for purchase of exchangeable senior note hedges	(28,676)	0	0
Proceeds from issuance of warrants	14,669	0	0
Payments for repurchase of exchangeable notes	(17,414)	0	0
Proceeds from notes payable to banks	0	0	24,671
Payments of notes payable to banks	0	(35,000)	(5,000)
Payment of notes payable to Mezzanine Lenders	0	0	(10,486)
Payment of unsecured notes payable to related and unrelated creditors	0	0	(5,489)
Payments of debt issuance costs	(5,300)	(168)	(266)
Proceeds from the exercise of Mezzanine Warrants and Junior Subordinated Notes Warrants	0	0	270
Proceeds from issuance of Class A common	82,901	111,687	0
Proceeds from issuance of Class A common stock sold in initial public offering, net of underwriting discounts and offering costs	0	0	89,506
Payments for Common Units in i3 Verticals, LLC from selling unitholders	(10,883)	(90,027)	(4,635)
Cash paid for contingent consideration	(3,492)	(2,634)	(977)
Payments for required distributions to members for tax obligations	(3)	(2,060)	0
Proceeds from stock option exercises	764	672	0
Payments for employee's tax withholdings from net settled stock option exercises	(310)	0	0
Net cash provided by financing activities	29,112	119,094	19,244
Net increase (decrease) in cash, cash equivalents, and restricted cash	17,401	1,963	(731)
Cash, cash equivalents, and restricted cash at beginning of period	3,200	1,237	1,968
Cash, cash equivalents, and restricted cash at end of period	20,601	3,200	1,237
Supplemental disclosure of cash flow information:
Cash paid for interest	5,250	4,911	7,881
Cash paid for income taxes	$ 792	$ 1,420	$ 483