NIM08710 - Earnings Periods: Payments not paid on their usual payday: Usual payday & date of payment in same tax year
Regulation 7(1)(a) & (2)(a) of the Social Security (Contributions) Regulations 2001 (SI 2001 No 1004)
If the usual payday and the date of the mistimed payment are in the same tax year, the employer should treat the early or late payment as if they had paid it at its usual time, for example if the employer pays two separate weeks’ wages at the same time, the payments must not be added together but NICs should be worked out on each payment separately.