Cask conditioned beer: Strength
The strength of cask beer can rise after it has been packaged.
Cask beer is racked into cask when fermentation is judged to be sufficiently complete. Secondary fermentation in cask may cause the actual ABV to increase. The addition of primings will add to this effect.
Duty is charged on the finished beer and the brewer must account for duty on the strength at which he expects the beer to be when it is consumed. The brewer can establish the strength that the beer will have attained at the optimum time for consumption by monitoring the strength in his sample cellar or, in the case of pub brewers, in the pub cellar.