Sole Sums works out your self assessment bill as a sole trader. Income tax, Class 4 National Insurance and student loan, plus the payment on account most people forget.
Free. No account, no bank linking. Your figures stay on your device. For 2025/26 (the return due 31 January 2027) and 2026/27.
Then by 31 July 2027£2,525.90
England, Wales or Northern Ireland, no student loan, first year in self assessment.
Same profit, but you already paid two £2,200.00 payments on account towards 2025/26.
Three steps. About two minutes if you know your rough figures.
Your income and expenses for the year, sorted into HMRC-style categories. Pick your student loan plan if you have one.
Income tax band by band, Class 4 National Insurance and student loan, using the GOV.UK rates for the year you pick. Scotland has its own bands.
Your 31 January bill, including the first payment on account, and your 31 July payment. Then tick off the ready-to-file checklist.
The estimate is free and always will be. Pro is a one-off purchase, not a subscription.
In-app purchase on iOS and Android. Pro on the web app is coming soon.
Tax year 6 April 2026 to 5 April 2027. Every figure below is from GOV.UK. The full comparison with 2025/26 is in our rates guide.
| Band | Income | Rate |
|---|---|---|
| Personal Allowance | Up to £12,570 | 0% |
| Basic | £12,571 to £50,270 | 20% |
| Higher | £50,271 to £125,140 | 40% |
| Additional | Over £125,140 | 45% |
| Band | Income | Rate |
|---|---|---|
| Personal Allowance | Up to £12,570 | 0% |
| Starter | £12,571 to £16,537 | 19% |
| Basic | £16,538 to £29,526 | 20% |
| Intermediate | £29,527 to £43,662 | 21% |
| Higher | £43,663 to £75,000 | 42% |
| Advanced | £75,001 to £125,140 | 45% |
| Top | Over £125,140 | 48% |
| Item | 2026/27 |
|---|---|
| Class 4 National Insurance | 6% on profits £12,570 to £50,270, then 2% above £50,270 |
| Class 2 National Insurance | Not compulsory. Treated as paid if profits are £7,105 or more. Voluntary rate £3.65 a week |
| Personal Allowance taper | Falls by £1 for every £2 of income over £100,000. Zero at £125,140 |
| Trading allowance | £1,000 a year |
| Student loan thresholds | Plan 1 £26,900, Plan 2 £29,385, Plan 4 £33,795, Plan 5 £25,000 (all 9%). Postgraduate £21,000 (6%) |
Sources: Income Tax rates and Personal Allowances, Scottish Income Tax, Self-employed National Insurance rates, Tax-free allowances on property and trading income, Rates and thresholds for employers 2026 to 2027. Checked 3 November 2026.
Yes. The tax estimate, the 31 January and 31 July payments, deadlines, the ready-to-file checklist and the income and expense log are all free. Pro is a one-off £4.99 in-app purchase on iOS and Android that adds CSV and PDF export, a mileage calculator and a use-of-home calculator. Pro on the web app is coming soon.
No. Sole Sums gives you an estimate and helps you get ready. You file your return through your HMRC online account or through HMRC-recognised software. See the 2027 deadlines.
2025/26 (6 April 2025 to 5 April 2026), the return due online by 31 January 2027, and 2026/27 (6 April 2026 to 5 April 2027).
Yes. It has the Scottish income tax bands for both years. Wales uses the same rates as England and Northern Ireland, so those three share one setting.
It is built for sole-trader profits and student loan repayments. It does not cover:
If any of those apply to you, your real bill will be different. Use HMRC's own calculation or speak to an accountant.
It uses the published GOV.UK rates for each year, checked on 3 November 2026, and HMRC's payment on account rules. It is still an estimate, not tax advice. Your HMRC calculation is the final word.
Only on your device. There is no account, no bank linking, no analytics and no tracking. We never see your figures. Read the privacy policy.
Class 2 is no longer compulsory since 6 April 2024. If your profits are at or above the small profits threshold (£6,845 for 2025/26, £7,105 for 2026/27) it is treated as paid. Below that you can choose to pay voluntarily, at £3.50 a week for 2025/26 or £3.65 a week for 2026/27.
Your income is your business. Sole Sums is built so we never see it.
Free in your browser now. The iPhone and Android apps are on their way.
