Ill. Admin. Code tit. 86, § 710.20
a) Prior to the disclosure of a delinquent taxpayer under the Act, the Department will deem the taxpayer delinquent and subject to disclosure under the Act, based upon the following criteria:
3) At least 6 months have passed from the time that the final tax liability was assessed or became final, as provided in the statute imposing the tax.
Taxpayers meeting each of these criteria shall be deemed "delinquent taxpayers" subject to disclosure.
(Source: Amended at 25 Ill. Reg. 16289, effective December 10, 2001)