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HMRC internal manual

National Insurance Manual

Earnings Periods: Payments not paid on their usual payday: Usual payday & date of payment in same tax year

Regulation 7(1)(a) & (2)(a), SS(C)R 2001

If the usual payday and the date of the mistimed payment are in the same tax year, theemployer should treat the early or late payment as if they had paid it at its usual time,eg if the employer pays two separate weeks’ wages at the same time, the payments mustnot be added together but NICs should be worked out on each payment separately.