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HMRC internal manual

National Insurance Manual

Earnings Periods: General: Alignment with tax weeks and months

Section 122 SSCBA 92 & Regulation 1, SS(C)R 2001

The definitions of an Income Tax week, month and year are as follows –

  • Income Tax weeks.

These are successive periods of 7 days, including Sundays, beginning with 6 April each year As the number of days in a tax year is not exactly divisible by seven, any remaining odd days at the end of the tax year are treated as a separate week – “week 53”.

  • Income Tax months.

These begin on the 6th day of one month and end on the 5th day of the next. The first tax month begins on 6 April

  • Income tax year.

These begin on the 6th April in one year and end on the 5th April in the next

Earnings periods for the majority of employees who are paid regularly are, in manyrespects, aligned with income tax periods. This is because the first earnings period forsuch employees always begins on the first day of the tax year.

The practical effect of this rule is that the earnings period for employees who arepaid regularly at intervals of a week will correspond with the income tax week. Similarly,for earners who are paid monthly their earnings period will correspond with the income taxmonth.


A weekly paid employee is paid each Friday with the first payment being made on Friday8th April 2005. The employee’s first earnings period in the 2005/2006 tax year starts onWednesday 6th April 2005 and ends on Tuesday 12th April 2005 - in line with income taxweek 1. The next earnings period begins on Wednesday 13th April 2005 - in line with incometax week 2.

Some employees, however, are paid regularly but at intervals that are not exact weeksor months. In such cases the prescribed earnings period will not correspond with an incometax week or month. An example would be an employee who is paid every ten days.Nevertheless the first earnings period for these earners will still begin on the first dayof the tax year.