01 May 2017
From The Brewers Association:
The Brewers Association Beer Style Guidelines are compiled for the Brewers Association (BA) by Charlie Papazian, copyright 1993 through and including 2017, with Style Guideline Committee assistance and review by Paul Gatza, Chuck Skypeck, Chris Swersey and suggestions from Great American Beer Festival® and World Beer Cup℠ judges.
Organizations or individuals that use the Brewers Association Beer Style Guidelines (“Guidelines”) must be aware that they are updated yearly with significant changes including editing, deletion and/or addition of beer styles. Changes are not tracked from year to year.
The updated version of the Guidelines is usually posted in February or early March each year. Therefore, Brewers Association recommends annual updates to products based on the Guidelines.
Full style guide is here.