27 CFR §27.44

Compounds and preparations, other than those specified in § 27.43 containing distilled spirits, which are fit for beverage purposes, in customs bonded warehouse or imported into the United States are subject to internal revenue tax at the rates applicable to distilled spirits. Compounds and preparations, containing fortified or unfortified wine, but no distilled spirits, which are fit for beverage purposes and which are sold as wine, are subject to internal revenue tax at the rates applicable to wines.