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HMRC internal manual

National Insurance Manual

Earnings Periods: Employee who usually works, and is paid, every other week/every other fortnight

If an employee usually works and is paid every other week or fortnight, the earningsperiod is two weeks or four weeks respectively. The earnings period remains as twoweeks/four weeks even if occasionally the employee works the whole fortnight/four weekperiod instead of every other week/fortnight and the employer pays the employee separatelyfor each week/fortnight.