A tax is imposed by 26 U.S.C. 5051 , on all beer imported into the United States, at the rate prescribed in such section, for every barrel containing not more than 31 gallons, and at a like rate for any other quantity or for fractional parts of a barrel. The tax on beer shall be determined at the time of importation, or, if entered into customs custody, at the time of removal from such custody.
27 C.F.R. § 27.45
Sec. 201, Pub. L. 85-859, 72 Stat. 1333, as amended, 1334, as amended ( 26 U.S.C. 5051 , 5054 )