Class 4 National Insurance contributions are a key part of the UK's tax system, specifically designed for self-employed individuals. Understanding these contributions is crucial for self-employed taxpayers as they impact eligibility for certain state benefits and affect tax liabilities. What Is Class 4 National Insurance in the UK? | Self-Employed NI Explained | PTA Understanding Class 4 NICs Class 4 NICs are levied on the profits earned from self-employment. As of the 2024-2