27 CFR 26.77: Subject to tax.

(a) Distilled spirits of Puerto Rican manufacture, and any products containing such distilled spirits, brought into the United States and withdrawn for consumption or sale are subject to a tax equal to the tax imposed in the United States by 26 U.S.C. 5001.

(b) A credit against the tax imposed on distilled spirits by 26 U.S.C. 7652 is allowable under 26 U.S.C. 5010 on each proof gallon of alcohol derived from eligible wine or from eligible flavors which do not exceed 2 1/2 percent of the finished product on a proof gallon basis. The credit is allowable at the time the tax is payable as if it constituted a reduction in the rate of tax.

(c) Where credit against the tax is desired, the person liable for the tax shall establish an effective tax rate in accordance with § 26.79a. The effective tax rate established will be applied to each withdrawal or other disposition of the distilled spirits for consumption or sale within the United States.