You stop paying National Insurance (NI) contributions in the UK primarily when you reach State Pension age, currently 66 for both men and women. At that point, you no longer have to pay Class 1 NI if you are employed, or Class 2 and Class 4 NI if you are self-employed, even if you continue working beyond State Pension age. You must inform your employer and provide proof of age to stop NI deductions from your wages. For self-employed individuals, Class 4 contributions stop at the end of the tax year in which you reach State Pension age, and Class 2 contributions have already been abolished from the 2024/25 tax year but were treated as paid up to the pension age if profits exceeded the threshold. Earnings below the NI threshold before reaching State Pension age mean no NI payments are required though credits may apply. Note that no NI is payable on pension income, but income tax still applies above allowances. If NI payments continue post-pension age, you can claim a refund from HMRC.