Consolidated Statements of Operations - USD ($) $ in Thousands		12 Months Ended
		Sep. 30, 2020	Sep. 30, 2019		Sep. 30, 2018
Income Statement [Abstract]
Revenue		$ 150,134	$ 376,307		$ 323,508
Operating expenses
Interchange and network fees		0	242,867	[1]	214,543	[1]
Other costs of services		47,230	44,237		40,314
Selling general and administrative		78,323	62,860		40,585
Depreciation and amortization		18,217	16,564		11,839
Change in fair value of contingent consideration		(1,409)	3,389		3,866
Total operating expenses		142,361	369,917		311,147
Income from operations		7,773	6,390		12,361
Other expenses
Interest expense, net		8,926	6,004		8,498
Change in fair value of warrant liability		0	0		8,487
Other expense		2,621	0		0
Total other expenses		11,547	6,004		16,985
(Loss) income before income taxes		(3,774)	386		(4,624)
(Benefit from) provision for income taxes		(2,795)	(177)		337
Net (loss) income		(979)	563		(4,961)
Net (loss) income attributable to non-controlling interest		(560)	3,608		1,937
Net loss attributable to i3 Verticals, Inc.		$ (419)	$ (3,045)		$ (6,898)
Net (loss) income per share attributable to Class A common stockholders
Basic (in USD per share)	[2]	$ (0.03)	$ (0.29)		$ 0.08
Diluted (in USD per share)	[2]	$ (0.03)	$ (0.29)		$ 0.08
Weighted average shares of Class A common stock outstanding
Basic (shares)	[1]	14,833,378	10,490,981		8,812,630
Diluted (shares)	[1]	27,429,801	10,490,981		26,873,878

[1] Effective October 1, 2019, the Company's revenues are presented net of interchange and network fees in accordance with Accounting Standards Codification Topic 606, Revenue from Contracts with Customers. See Note 2 to our consolidated financial statements for a description of the recently adopted accounting pronouncement.

[2] Basic and diluted net income per share of Class A common stock are presented only for the period after the Company’s Reorganization Transactions. See Note 1 for a description of the Reorganization Transactions. See Note 18 for the calculation of income per common share.