DISCONTINUED OPERATIONS - Income (Loss) From Discontinued Operations (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Operating expenses
Change in fair value of contingent consideration	$ (374)	$ 1,377
Net (loss) income from discontinued operations attributable to non-controlling interest	(46)	117
Net (loss) income from discontinued operations attributable to i3 Verticals, Inc.	(92)	201
Healthcare RCM Business \| Discontinued Operations, Held-for-Sale or Disposed of by Sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenue	0	9,736
Operating expenses
Other costs of services (excluding depreciation and amortization)	0	5,721
Selling, general and administrative	0	2,421
Depreciation and amortization	0	823
Change in fair value of contingent consideration	0	125
Total operating expenses	0	9,090
Income from operations	0	646
Other expenses	169	0
(Loss) income before income taxes from discontinued operations	(169)	646
Benefit from income taxes	(31)	114
Net (loss) income from discontinued operations	(138)	532
Net (loss) income from discontinued operations attributable to non-controlling interest	(46)	193
Net (loss) income from discontinued operations attributable to i3 Verticals, Inc.	$ (92)	339
Merchant Services Business \| Discontinued Operations, Held-for-Sale or Disposed of by Sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenue		0
Operating expenses
Other costs of services (excluding depreciation and amortization)		0
Selling, general and administrative		0
Depreciation and amortization		0
Total operating expenses		0
Income from operations		0
Interest expense, net		0
Other expenses		253
Total other expenses		253
(Loss) income before income taxes from discontinued operations		(253)
Benefit from income taxes		(39)
Net (loss) income from discontinued operations		(214)
Net (loss) income from discontinued operations attributable to non-controlling interest		(76)
Net (loss) income from discontinued operations attributable to i3 Verticals, Inc.		$ (138)

i3 Verticals, Inc. 10-Q