Regulation 5 of the Gaming Duty Regulations 1997 (S.I. 1997/2196) specifies the amount of the payment on account of gaming duty. Payments on account are required to be made by a registered provider (as defined in regulation 2 of the Gaming Duty Regulations 1997) in respect of the first three months of any six month accounting period.
Link: The Gaming Duty (Amendment) Regulations 2018
Source: Legislation .gov.uk
