No refund of an overpayment of any amount imposed by this article shall be allowed in whole or in part unless a claim for refund is filed with the collector within a period of year from the last day of the calendar month following the period for which the overpayment was made, and all such claims for refund of the amount of the overpayment shall be filed with the collector on forms furnished by and in the manner prescribed by the collector. Upon the filing of such a claim, and when the collector determines that an overpayment has been made, the collector may refund the amount overpaid. (Ord. No. 1006, § 2 (part); Ord. No. 1228, § 4.)