Self Assessment Tax Calculator
Work out your self-assessment tax bill for 2025/26. Covers income tax, Class 2 and Class 4 National Insurance, and payments on account.
Total Tax Due
£8,611.20
On taxable income of £32,430.00
Full Breakdown
| Self-employed income | £50,000.00 |
| Less: allowable expenses | -£5,000.00 |
| Trading profit | £45,000.00 |
| Other income | £0.00 |
| Total income | £45,000.00 |
| Personal allowance | £12,570.00 |
| Taxable income | £32,430.00 |
| Income tax | £6,486.00 |
| Class 2 NI | £179.40 |
| Class 4 NI | £1,945.80 |
| Total NI | £2,125.20 |
| Total due | £8,611.20 |
| Payment on account (each) | £4,305.60 |
About Self Assessment
If you are self-employed, you must file a self-assessment tax return by 31 January following the end of the tax year. You pay income tax on your trading profits plus Class 2 and Class 4 National Insurance.
Class 2 NI is a flat weekly rate (£3.45/week in 2025/26) payable if profits exceed £12,570. Class 4 NI is 6% on profits between £12,570 and £50,270, and 2% on profits above that.
If your bill exceeds £1,000, HMRC requires payments on account -- two advance payments of 50% each, due 31 January and 31 July.
Last updated: May 2026. Uses 2025/26 tax rates and thresholds.
Built by The NexoraOS Team