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HMRC internal manual

Decisions and appeals for National Insurance Contributions and Statutory Payments

Notices of decision: Wording of National Insurance contributions liability decisions: Estimating earnings when calculating Class 1 National Insurance contributions liability

DANSP31100 provides some general information about calculating Class 1 National Insurance contributions (NIC) liability decisions where the NIC due are more than the NIC paid.

In some cases you will have no choice but to estimate the earnings on which NIC are due. Social Security legislation allows you to do this. It does not allow you to estimate the NIC due - you must accurately calculate the NIC due on those estimated earnings.

Cases in which you will have to estimate the earnings include those where

  • there are no records available - perhaps because they have been destroyed,
  • the employer refuses to provide documents to enable you to calculate the NIC due and using your powers to obtain the documents has proved unsuccessful.