26 CFR § 48.6421-5 - Exempt sales; other payments or refunds available.
(a) Exempt sales. No credit or payment shall be allowed or made under § 48.6421–1 or § 48.6421–2 with respect to gasoline which was exempt from the tax imposed by section 4081. For example, credit or payment may not be allowed or made with respect to gasoline purchased tax free for use as supplies for certain vessels and airplanes, or with respect to gasoline purchased by a State tax free for its exclusive use, as provided in section 4221.
(b) Other payments or refunds available. Any amount which, without regard to the second sentence of section 6421(e)(1) and this paragraph (b), would be allowable as a credit or payable to any person under § 48.6421–1 or § 48.6421–2 is reduced by any other amount which is allowable as a credit or payable under section 6421, or is refundable under any other provision of the Code, to any person with respect to the same gasoline.
(c) Gasoline used on farms. Payments with respect to gasoline used on a farm for farming purposes shall be claimed under section 6420 and § 48.6420–1, and no claim in respect of that gasoline may be made under section 6421 and the regulations thereunder.