Earnings Periods: Change of earnings period with the same employer: Change to shorter interval
Regulation 18, SS(C)R 2001
If an employees regular earnings period changes to a shorter interval, eg monthlyto weekly paid, or quarterly to monthly paid, work out the NICs on payments made after thechange using the earnings period for the new interval.
A monthly paid employee changes to weekly paid on the first day of the month havingreceived a monthly salary the day before. They receive their first weekly pay on the 5th.Although this payment is in the same tax month as their monthly salary, work out the NICsfor this payment separately using a weekly earnings period.