What are the UK regulations on bottle fill tolerances and declared volumes for duty and trading standards purposes?

Fill tolerance in the UK is split between two regulators. HMRC allows a 5% tolerance on duty calculations, which applies to the litres of pure alcohol (LPA) declared—there is no tolerance on the duty itself, only on allowable losses in production. Trading standards and local authorities enforce weights and measures under packaged goods regulations via gov.uk/weights-measures-and-packaging-the-law/packaged-goods. The key distinction is whether you pack to a minimum or an average: if you declare a minimum (e.g. "70cl minimum"), you cannot go under that figure; if you pack to average (marked with an epsilon symbol €), there is a tolerance up and down. However, if you knowingly overfill beyond the stated volume, you cannot claim tolerance—you must keep records of your fill process. Some members have successfully used 75cl bottles underfilled to 70cl equivalent for UK sale without issues from trading standards, provided filling records are maintained and inspections have cleared them. Industry data suggests beer has tighter tolerances (around 0.5%) and spirits around 0.3%, though these appear to be best-practice rather than hard regulatory ceilings.