NI Class 2 vs Class 4 Contributions Comparator
Compare your Class 2 and Class 4 National Insurance contributions as a self-employed individual based on your annual profit. Uses 2024/25 HMRC rates.
Formulas Used
Class 2 NI (2023/24):
If profit ≥ Small Profits Threshold (SPT): Class 2 = Weekly Rate × 52
If profit < SPT: Class 2 = £0 (voluntary contributions only)
Class 2 NI (2024/25):
Effectively abolished — self-employed with profits ≥ SPT receive NI credit at no cost.
Class 4 NI:
Lower Band = (min(Profit, UPL) − LPL) × Lower Rate [if Profit > LPL]
Upper Band = (Profit − UPL) × Upper Rate [if Profit > UPL]
Total Class 4 = Lower Band + Upper Band
Total NI = Class 2 + Total Class 4
Effective Rate = Total NI ÷ Profit × 100
| Parameter | 2023/24 | 2024/25 |
|---|---|---|
| Class 2 Weekly Rate | £3.45 | £0 (abolished) |
| Small Profits Threshold (SPT) | £12,570 | £6,725 |
| Lower Profits Limit (LPL) | £12,570 | £12,570 |
| Upper Profits Limit (UPL) | £50,270 | £50,270 |
| Class 4 Lower Rate | 9% | 6% |
| Class 4 Upper Rate | 2% | 2% |
Assumptions & References
- Rates are based on HMRC published figures for 2023/24 and 2024/25 tax years.
- Class 2 NI was effectively abolished from 6 April 2024 (Spring Budget 2024). Self-employed individuals with profits at or above the SPT receive a NI credit without paying Class 2.
- Class 4 NI lower rate was reduced from 9% to 6% from 6 April 2024 (announced Autumn Statement 2023).
- Profit is defined as self-employed trading profit after allowable expenses but before personal allowance deductions.
- This calculator does not account for Employment Allowance, pension contributions, or other reliefs.
- Class 1 NI (employed earnings) is not included in this comparison.
- Voluntary Class 2 contributions (for those below SPT) are not calculated here.
- References: HMRC — Self-employed National Insurance rates; Spring Budget 2024; Autumn Statement 2023.