Taxation: administration; calculation of interest and penalties related to the issuance of certain refunds; provide for. Amends sec. 30 of 1941 PA 122 (MCL 205.30).

This bill updates Michigan state law to require the Department of Treasury to pay interest on tax refunds that are delayed beyond specific timeframes. It directly affects taxpayers who have filed complete and timely income tax returns and are awaiting refunds. Under the new rules, refunds for Michigan income taxes will automatically earn interest if they are not processed within 30 or 60 days of the department receiving the return, depending on when the return was filed. The bill also establishes a penalty of $100 for refunds delayed more than 90 days and sets a fixed 3% annual interest rate for a temporary period before switching to a variable rate tied to the prime rate. These provisions apply only to straightforward refunds without errors, audits, or suspected fraud, ensuring the state compensates citizens for administrative delays.