Self Employed Tax UK 2025/26: Profit, NI, and Payments on Account
How trading profit turns into income tax and National Insurance for sole traders and freelancers — trading allowance, Class 2 and Class 4 NI, personal allowance taper, and why payments on account change your cash flow. Pairs with our free self employed tax calculator (2025/26). England, Wales, and Northern Ireland income tax only. For general information only — not professional advice.
1. How this fits with our expenses guide
If you are looking for which costs you can claim (software, travel, home office, and so on), our self-employed expenses guide is the right place. This article is the companion piece: it explains what happens after you know your turnover and allowable expenses — how HMRC-style figures for income tax and self-employed National Insurance apply to your trading profit in 2025/26, and how payments on account affect when you actually pay.
Together, "what can I claim?" and "how much tax on what's left?" answer the searches many sole traders run at different stages of the year.
2. Trading profit (the starting point)
For many sole traders using a simple picture, trading profit is:
Annual turnover − annual allowable business expenses = trading profit
That profit is broadly what income tax and Class 4 NICs are based on (subject to reliefs, other income, losses brought forward, accounting periods, and how you prepare figures — your accountant handles the detail).
Our self employed tax calculator asks for turnover and allowable expenses so you can see a stylised annual estimate of tax, Class 4, and profit after those deductions.
3. The £1,000 trading allowance
HMRC offers a trading allowance of up to £1,000 per tax year for some trading income. Depending on your circumstances, you may be able to deduct this allowance from your gross trading income instead of deducting your actual business expenses — but you cannot mix and match in the same way as claiming full expenses on the same basis. Rules differ if you have multiple trades or other income.
If your gross trading income is £1,000 or less, the allowance may mean you have no taxable trading income from that source (again, subject to rules and registration). If it is higher than £1,000, you might still use the allowance as a flat £1,000 deduction instead of recording every receipt — or you might be better off with actual expenses if they exceed £1,000.
The calculator assumes you enter total allowable expenses already net of your chosen method (i.e. it does not toggle trading allowance for you). If you use the allowance in your real tax return, adjust inputs or treat the result as illustrative. See Tax-free allowances on property and trading income on gov.uk.
4. Income tax on your profit (2025/26)
For England, Wales, and Northern Ireland, income tax on your taxable profit uses the same band structure as employment income (after your personal allowance and any taper). For 2025/26 the standard personal allowance remains £12,570. Above £100,000 it usually tapers by £1 for every £2 of income until it can reach nil around £125,140 (with standard allowance and no other complexity).
Taxable profit for this simple model is trading profit minus personal allowance (and the calculator assumes trading profit is your main figure for tapering). Tax is then charged on taxable income in slices:
| Band | Taxable profit (after allowances) | Rate |
|---|---|---|
| Basic rate | £0 to £37,700 | 20% |
| Higher rate | £37,701 to £112,570 | 40% |
| Additional rate | Above £112,570 | 45% |
Scottish taxpayers: different bands and rates apply to your non-savings, non-dividend income. For PAYE comparison, see our UK income tax rates guide and income tax calculator.
5. Class 4 National Insurance
Class 4 is calculated from your annual trading profits (before income tax). For 2025/26, the same annual thresholds as in our calculator are:
| Annual profit | Class 4 rate |
|---|---|
| Up to £12,570 | 0% |
| £12,571 to £50,270 | 6% |
| Above £50,270 | 2% on profits above £50,270 |
So once profit moves past the lower profits limit, you often feel income tax plus 6% Class 4 in the same stretch of income — that is why “how much tax self employed?” feels higher than PAYE headline rates alone.
6. Class 2 National Insurance (2025/26 rules)
Class 2 used to be a small fixed weekly liability for many self-employed people. From 6 April 2024, the requirement to pay Class 2 was removed for a large group of earners, with National Insurance credits available in certain profit bands instead — see HMRC. Our calculator therefore shows mandatory Class 2 cash as £0 for 2025/26 in line with that mainstream simplification.
If your profits are below the small profits threshold — £6,845 for 2025/26 on the figures we use — you may still choose to pay Class 2 voluntarily to help protect benefit entitlements. The illustrative voluntary weekly rate for 2025/26 used in our calculator copy is £3.50 (about £182 a year if paid for all 52 weeks). This is not added to our main “profit after tax” total unless you pay it in practice.
Official wording changes quickly — confirm on Self-employed National Insurance rates.
7. Rough effective tax rates (why it stacks up)
Sole traders often compare themselves to friends on PAYE. On employment income you pay income tax and Class 1 NI; on profit you pay income tax and Class 4. The percentages are different, and they apply to different bases — but in the mid-profit range it is common to see a combined marginal bite of roughly 20% income tax plus 6% Class 4 (26%) on profit above the personal allowance and Class 4 thresholds, before you hit higher-rate income tax (where the stack jumps again).
An effective rate (total income tax plus NI, divided by profit) is lower than those marginal slices because the first slice of profit may be sheltered by the personal allowance and the Class 4 nil band. Our calculator shows an illustrative effective rate for exactly that reason.
Try different turnover and expense figures in the self employed tax calculator to see how sensitive your outcome is to claiming one more £1,000 of allowable costs — another reason the expenses guide matters.
8. Payments on account
When people ask “how much tax do I owe?” they sometimes mean 31 January balancing payment or July/January instalments. Once your Self Assessment bill exceeds a threshold, HMRC usually requires payments on account: two advance payments towards next year's bill (typically each set at half of your previous year's liability), with a reconciliation when you file the next return.
Your first year of serious self-employment often has no payments on account precedent, so January can feel steep; later years spread more of the load into July and the following January. None of that instalment timing is shown in our annual calculator — the tool is a profit-to-tax snapshot, not a cash-flow planner.
Read Understand your Self Assessment bill on gov.uk (covering payments on account and balancing payments).
9. What our calculator includes — and what it does not
- ✓Includes: turnover minus expenses you enter, personal allowance with £100k taper, England/Wales/NI income tax bands for 2025/26, Class 4 NIC at 6% / 2% with thresholds £12,570 / £50,270, mandatory Class 2 shown as £0 (mainstream 2024 rule change).
- ✗Does not include: payments on account, student loans, High Income Child Benefit Charge, pension contributions, other income (employment, dividends, property), losses carried forward, partnership rules, or accounting period differences. Trading allowance is not a toggle — adjust inputs if you use it.
For a full liability you still need Self Assessment (or an accountant). The calculator is there to orient you and answer “what-if” on profit.
10. Frequently asked questions
How much tax do I pay if I am self employed in the UK?
Broadly, you pay income tax on your taxable profit (after personal allowance and reliefs) and Class 4 National Insurance on trading profits above the lower profits limit. Class 2 is not usually paid as a separate fixed weekly amount for most people from April 2024, but voluntary Class 2 may apply if profits are very low — see gov.uk. The exact amount depends on your profit, other income, reliefs, and whether you use the trading allowance. Use our self employed tax calculator for a simplified annual estimate.
What is the trading allowance for self-employed people?
The trading allowance can give you up to £1,000 per tax year off your gross trading income before calculating profit, instead of deducting your actual business expenses — but only if you are eligible and choose to use it. You cannot use the trading allowance and also deduct actual expenses for the same income in the same way. If your gross trading income is £1,000 or less, the allowance may cover it entirely. Always check HMRC rules or an accountant for your situation.
What are Class 2 and Class 4 National Insurance for 2025/26?
Class 4 is charged on annual trading profits: for 2025/26, typically 6% on profits between £12,570 and £50,270 and 2% on profits above £50,270 (same thresholds as in our calculator). Class 2 was historically a flat weekly charge; from 6 April 2024 mandatory Class 2 was removed for many self-employed people, with credits in certain profit bands. If profits are below the small profits threshold (£6,845 for 2025/26 in HMRC figures), you may pay Class 2 voluntarily (2025/26 illustrative rate £3.50 per week) to protect entitlement to some benefits — confirm on gov.uk.
What are payments on account for Self Assessment?
If your Self Assessment tax bill is high enough, HMRC usually asks for payments on account towards next year's bill — typically two instalments in July and January, each based on your previous year's liability. You may still owe a balancing payment by the following 31 January. This cash-flow pattern means the tax you pay in-year can differ from a simple annual profit calculation.
Does this guide cover Scotland?
Income tax rates and bands on non-savings, non-dividend income are set separately for Scottish taxpayers. Class 4 National Insurance rules are UK-wide. Our self employed tax calculator uses England, Wales, and Northern Ireland income tax bands.
Where can I read about allowable expenses (not tax on profit)?
Our companion article on what expenses you can claim as self-employed covers categories like travel, equipment, and home office — it complements this piece, which focuses on how profit turns into tax and NI. See the link in the article to “What Expenses Can I Claim as Self-Employed in the UK”.
11. Important disclaimer
This article is for general information only. It is not tax, legal, or accounting advice. Self-employment rules, National Insurance, and allowances change — verify everything on gov.uk or with a qualified adviser. We accept no liability for reliance on this content.
Official HMRC references
Model your profit and tax
Try our free self employed tax calculator for 2025/26 — turnover, expenses, income tax, and Class 4 NI (illustration only).