Class 4 national insurance contributions are paid by self-employed individuals (including partners in partnership) working in the UK1. Class 4 contributions are calculated based on a percentage of the individual's trading profits and are reported and collected via the individual's self assessment tax return. Class 4 contributions are not deductible to any extent from business profits for income tax purposes2.
For an overview of Class 4 contributions, see E8.316. For the rate of Class 4 contributions, see E8.318.
The self-employed may also be liable to pay Class 2 national insurance contributions, which are a weekly contribution also collected via the self assessment return3. See E8.301.
This article explains how to reclaim overpaid Class 4 contributions.
Claiming a refund of overpaid Class 4 contributions
Where payment is made in excess of the contributor's liability, or in error, and
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Web page updated on 17 Mar 2025 17:30