This part of GOV.UK is being rebuilt – find out what beta means

HMRC internal manual

VAT Food

Items benefiting from the relief: what is food?: food packaging: promotional offers

Where an item of packaging is held out as a promotional offer (for instance, a free mug), this is always a separate supply and VAT should be charged on the proportion of the price relating to the packaging, unless the linked goods concession (VFOOD2840) applies.