Rev. Ruling 54-526
Solids Content of Wine Limitations are not applicable to Vermouth or Aperitif Wines
The limitations and requirements of Regulation No. 4 and Regulations 7 with respect to the solids content of wine are not applicable to vermouth or aperitif wines.
26 U.S.C. 3036 (Internal Revenue Code of 1939); 26 CFR 178.182 (27 CFR 240.444)