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

HMRC internal manual

VAT Betting and Gaming Guidance

Machine games: what is a machine game?: machine offering both dutiable and non-dutiable machine games

Where a machine offers both dutiable machine games and other activities (e.g. relevant machine games), then the net takings from the dutiable machine games will be VAT exempt and the remainder will be subject to VAT. A direct attribution should be made between payments and winnings to the relevant supplies. However, where that is not practicable then any reasonable attribution or apportionment may be made.