The Free Mash Tun Act Reshapes British Beer Taxation

On August 12, 1880, the Inland Revenue Act received royal assent in the United Kingdom. Commonly known as the Free Mash Tun Act, it repealed the longstanding excise duty on malt and replaced taxation of brewing materials with a duty on the beer produced. The new duty was calculated from the quantity and original gravity of the wort, shifting the fiscal focus from the amount of malt used to the potential yield of the finished beer. The reform gave brewers greater freedom to use grains, sugar, and other fermentable materials instead of structuring recipes around the malt tax. It therefore changed both brewery accounting and recipe formulation, while subjecting brewhouses to detailed measurement, recordkeeping, and excise supervision. The Act became a major turning point in British brewing taxation and helped establish original gravity as a central measure in the regulation of beer.