27 CFR 24.290: Removal of wine as distilling material.

(a) General. Still wine or still hard cider may be removed without payment of tax to the production facilities of a distilled spirits plant for use as distilling material. The volume of distilling material may be determined at either the bonded wine premises or the distilled spirits plant.

(b) Special natural wine. Unmarketable special natural wine may be removed to a distilled spirits plant for use as distilling material in the production of wine spirits (but not brandy). Where sugar has been used in the production of special natural wine, the wine may not be removed for use as distilling material if the unfermented sugars therein have been fermented prior to the removal. If wine spirits produced from special natural wine contain any flavor characteristics of the special natural wine, the wine spirits may be used only in the production of a special natural wine.