If it shall appear that an amount of tax has been paid which was not due under the provisions of this subchapter, whether as the result of a mistake of fact or an error of law, then such amount shall be credited against any tax due, or to become due, under this subchapter from the taxpayer who made the erroneous payment; provided that no amounts erroneously paid more than three years prior to the filing of a claim therefor shall be so credited.
('69 Code, § 19-50) (Ord. 0-66-17, passed 11-30-66)