Some wineries offer classes such as tasting and evaluating wines, pairing wines, or the winemaking process. How this income is taxable depends on what the customer receives in exchange for the registration fee.
Income from classes that include retail services, such as food or wine tasting, is subject to B&O tax under the Retailing classification and you must collect sales tax.
Charges for primarily instructional classes, such as wine making or home brewing, that do not include goods or retail services are not subject to sales tax. Gross income from these classes is subject to B&O tax under the Service and Other Activities classification.
RCW 82.04.050 “Sale at retail,” “retail sale.”