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HMRC internal manual

National Minimum Wage Manual

Issuing notices of underpayment: rounding time & monetary amounts on a notice

National minimum wage legislation is not prescriptive regarding how time and monetary amounts are displayed on a notice of underpayment.

It is appropriate that any decimal figures presented on a notice of underpayment should be restricted so that only two decimal places are displayed. However, care should be taken to avoid using rounded figures within calculations as they can introduce rounding errors. For improved accuracy, it is preferable to retain all decimal places throughout all stages of a calculation, such as for individual pay reference periods, so that any rounded total figures will be based on more decimal places than displayed.


When calculating the hours worked in a pay reference period obtain the total time worked in hours and minutes. Show minutes as a decimal of an hour by dividing the minutes by 60.

For example:

  • 1 hour and 40 minutes is equivalent to 1.666 recurring and should be shown as rounded to 1.67 hours.


Round monetary amounts shown as pounds and pence to two decimal places in each pay reference period.

For example:

  • £32.475 should be shown as rounded to £32.48.