Worked example (2025/26)
Lives in England, self-employed turnover of £52,000 less £7,000 of expenses. The calculator above opens with these figures; change them to see your own tax calculation, laid out like the SA302 calculation HMRC sends you.
| Form | Tax calculation | Amount |
|---|---|---|
| SA103 | Profit from self-employment | £45,000.00 |
| Total income received | £45,000.00 | |
| Personal Allowance | −£12,570.00 | |
| Total income on which tax is due | £32,430.00 | |
| Basic rate 20% on £32,430 | £6,486.00 | |
| Income Tax charged | £6,486.00 | |
| Income Tax due | £6,486.00 | |
| Class 4 National Insurance | £1,945.80 | |
| Total tax, NI and student loan due | £8,431.80 | |
| Balance to pay | £8,431.80 | |
| Each payment on account for next year | £4,215.90 | |
| Total due by 31 January (balance + first payment on account) | £12,647.70 |
Tax and National Insurance by profit (2025/26)
| Profit | Income Tax | Class 4 NI | Total | Share of profit | Each payment on account |
|---|---|---|---|---|---|
| £15,000 | £486.00 | £145.80 | £631.80 | 4.2% | £0.00 |
| £25,000 | £2,486.00 | £745.80 | £3,231.80 | 12.9% | £1,615.90 |
| £35,000 | £4,486.00 | £1,345.80 | £5,831.80 | 16.7% | £2,915.90 |
| £50,000 | £7,486.00 | £2,245.80 | £9,731.80 | 19.5% | £4,865.90 |
| £60,000 | £11,432.00 | £2,456.60 | £13,888.60 | 23.1% | £6,944.30 |
| £80,000 | £19,432.00 | £2,856.60 | £22,288.60 | 27.9% | £11,144.30 |
| £100,000 | £27,432.00 | £3,256.60 | £30,688.60 | 30.7% | £15,344.30 |
| £125,000 | £42,432.00 | £3,756.60 | £46,188.60 | 37% | £23,094.30 |
| £150,000 | £53,703.00 | £4,256.60 | £57,959.60 | 38.6% | £28,979.80 |
Class 2 National Insurance is no longer charged: profits above £6,845 count towards your State Pension automatically, and below that you can pay £3.50 a week voluntarily.
How the Self Assessment calculation works
- Add up your income. Pay and benefits from employment (less allowable expenses), self-employed profit, rental profit, pensions and other income, then interest and dividends.
- Work out adjusted net income. Total income less grossed-up Gift Aid and personal pension contributions. It decides the Personal Allowance taper above £100,000 and the Child Benefit charge.
- Take off allowances. The £12,570 Personal Allowance (less £1 for every £2 over £100,000), Blind Person’s Allowance and any Marriage Allowance you transfer, set against income in the order that gives the least tax.
- Tax non-savings income at 20%, 40% and 45%, with the bands widened by Gift Aid and pension contributions.
- Tax savings after the £5,000 starting rate band and the Personal Savings Allowance, then dividends after the £500 dividend allowance.
- Take off reliefs such as the Marriage Allowance reduction and 20% relief for residential finance costs, then add the High Income Child Benefit Charge.
- Add Class 4 National Insurance, student loan repayments and Capital Gains Tax, take off tax already paid, and work out payments on account for next year.
Self Assessment rates and allowances
| Item | 2025/26 | 2026/27 |
|---|---|---|
| Personal Allowance | £12,570 | £12,570 |
| Basic rate (20%) on taxable income up to | £37,700 | £37,700 |
| Additional rate (45%) on taxable income over | £125,140 | £125,140 |
| Scottish bands (taxable income tops: starter / basic / intermediate / higher / advanced) | £2,827 / £14,921 / £31,092 / £62,430 / £125,140 | £3,967 / £16,956 / £31,092 / £62,430 / £125,140 |
| Dividend allowance and rates | £500; 8.75% / 33.75% / 39.35% | £500; 10.75% / 35.75% / 39.35% |
| Personal Savings Allowance (basic / higher) | £1,000 / £500 | £1,000 / £500 |
| Class 4 NI | 6% from £12,570, 2% over £50,270 | 6% from £12,570, 2% over £50,270 |
| Capital Gains Tax exempt amount and rates | £3,000; 18% / 24% (BADR 14%) | £3,000; 18% / 24% (BADR 18%) |
| Child Benefit charge starts / full | £60,000 / £80,000 | £60,000 / £80,000 |
| Student loan thresholds (Plan 1 / 2 / 4 / 5 / Postgraduate) | £26,065 / £28,470 / £32,745 / — / £21,000 | £26,900 / £29,385 / £33,795 / £25,000 / £21,000 |
| Online return and payment due | 31 Jan 2027 | 31 Jan 2028 |
Official source: Income Tax rates and allowances (GOV.UK), Scottish Income Tax (GOV.UK), Tax on dividends (GOV.UK), National Insurance rates (GOV.UK), Capital Gains Tax rates (GOV.UK), High Income Child Benefit Charge (GOV.UK), Student loan thresholds (GOV.UK), SA110 Tax calculation summary notes 2026 (HMRC). Rates checked on Oct 29, 2026.
Questions people ask
Do I need to file a return as a sole trader?
Yes, if your self-employed income was more than £1,000 in the tax year. Below that the trading allowance covers it.
Can I use the £1,000 trading allowance and claim expenses?
No. You either deduct the £1,000 allowance or your actual expenses, whichever is better.
When do I pay?
The balance for 2025/26 and the first payment on account for next year are due on 31 January 2027; the second payment on account is due on 31 July.
Is this the same as HMRC’s calculation?
It follows HMRC’s working sheet for the tax calculation (the SA110 notes) step by step, including setting your Personal Allowance against savings or dividends when that lowers the tax. It does not cover losses, foreign income, partnerships, trusts, life policy gains, the pension annual allowance charge or EIS/SEIS/VCT relief.
Which tax year should I choose?
2025/26 is the year from 6 April 2025 to 5 April 2026; its online return is due by 31 January 2027. 2026/27 runs to 5 April 2027 and is due by 31 January 2028.
Reviewed by Soufyane S.. Last updated Oct 29, 2026. How we check numbers
Estimates for information only, not tax, legal or financial advice. Check with an adviser or the official tax authority.