Iowa Code § 452A.72: Refund for fuel taxes erroneously or illegally collected or paid.

1. If any fuel taxes, penalties, or interest have been erroneously or illegally collected by the appropriate state agency from a licensee, the appropriate state agency may apply the overpayment against any tax liability outstanding on the books of the department against the claimant, or shall certify the amount to the director of the department of administrative services, who shall draw a warrant for the certified amount on the treasurer of state payable to the licensee. The refund shall be paid to the licensee immediately.

2. A refund shall not be made under this section unless a written claim setting forth the circumstances for which the refund should be allowed is filed with the appropriate state agency within three years from the date of the payment of the taxes erroneously or illegally collected or paid.

3. However, if it is found during an examination by the appropriate state agency that a licensee paid, as a result of a mistake, an amount of tax, penalty, or interest which was not due, and the mistake is found within three years of the overpayment, the appropriate state agency shall credit the amount against any penalty, interest or taxes due or shall refund the amount to the person.