Matthew's Journal

emperor is correct. Duty is paid when the beer leaves the brewery; Customs agrees with each brewery a nominal quantity of saleable beer per container (i.e. how much ullage allowance there is; breweries that sell more dry-hopped beer may get a larger allowance because there's more waste), and this is paid by the brewery on every cask they
sell.

If a pub manages to sell more pints from a cask than there are in it, through giving short measure, they get all the benefit and the government doesn't get any.