Is there anything in Illinois law that restricts a bank from reversing a dormancy fee?

We are not aware of any law that would prevent your organization from charging or reversing the charge of a dormancy fee. Generally, Illinois law permits a bank to determine an appropriate dormancy fee in accordance with the bank’s prudent business judgment and safe and sound operating standards. 205 ILCS 5/5e(b). If an account has been inactive long enough to be deemed “abandoned” and remitted to the State Treasurer, the Uniform Disposition of Unclaimed Property Act [Repealed effective 1/1/18] allows banks to withhold any lawful charges from such accounts, including dormancy fees. 765 ILCS 1025/2(a) [Repealed effective 1/1/18]. (The related regulations provide more detail on what types of charges can be deducted from abandoned accounts. 74 Ill. Adm. Code 760.60.)