Cover - USD ($) $ in Thousands	6 Months Ended
	Mar. 31, 2020	May 11, 2020	Sep. 30, 2019
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Transition Report	false
Entity File Number	001-38532
Entity Registrant Name	i3 Verticals, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	82-4052852
Entity Address, Address Line One	40 Burton Hills Blvd., Suite 415
Entity Address, City or Town	Nashville
Entity Address, State or Province	TN
Entity Address, Postal Zip Code	37215
Local Phone Number	465-4497
City Area Code	615
Title of 12(b) Security	Class A Common Stock, $0.0001 Par Value
Trading Symbol	IIIV
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Shell Company	false
Entity Central Index Key	0001728688
Current Fiscal Year End Date	--09-30
Document Period End Date	Mar. 31, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q2
Amendment Flag	false
Entity Ex Transition Period	false
Deferred tax asset	$ 35,334		$ 28,138
Long-term tax receivable agreement obligations	$ 25,773		$ 23,204
Class A Common Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		15,048,918
Class B Common Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		12,401,621