26 CFR 301.7507-6 - Abatement and refund.
(a) An assessment or collection, no matter when made, if contrary to section 7507, is subject to abatement or refund within the applicable statutory period of limitations.
(b) Collection from a bank within section 7507(b) which diminishes assets necessary for payment of depositors, if made prior to agreement with depositors, is not contrary to the section, and affords no ground for refund.
(c) Any abatement or refund is subject to existing statutory periods of limitation, which periods are not suspended or extended by section 7507. In order to secure a refund of any taxes paid for any taxable year during the period of immunity the bank must file claim therefor.