If you have reached the State Pension age and continue to work, in most cases you no longer need to pay employees National Insurance Contributions (NICs).
At State Pension age, the requirement to pay Class 1 and Class 2 NICs ceases. However, you will remain liable to pay any NICs due to be paid to you before reaching the State Pension age. If you continue working, you will need to provide your employer with proof of your age.
Your employer remains liable to pay secondary Class 1 employer NICs. If you would rather not provide proof of age to your employer you can request a letter (known as an age exception certificate) from HMRC confirming, you have reached State Pension age and are no longer required to pay NICs.
If you are self-employed you will need to pay Class 4 NICs for the remainder of the year in which you reach State Pension age but will be exempt from the following year.
HMRC provides the following example if you reach State Pension age on 6 September 2021. You will stop making Class 4 contributions on 5 April 2022 and pay your final Class 4 bill by 31 January 2023, together with your Income Tax.
If you have overpaid NICs you can claim the excess back from HMRC.