I know that Regulation CC does not apply to transaction holds on savings accounts, but are there any Illinois laws that might apply?

We are not aware of any restrictions on placing holds on items deposited into a savings account (provided that the account falls into the Regulation CC definition of “savings account,” which refers to the definition of that term in 12 CFR 204.2). To our knowledge, no Illinois laws impose additional requirements on deposits into bank accounts. Also, if your institution has agreed to follow the Regulation CC funds availability requirements for its savings accounts voluntarily (for example, in an account agreement or signature card), it will have to honor those provisions.