UK Self-Employed Tax Calculator (Income Tax + Class 4 NI)
Your Self Assessment bill as a sole trader, and what to set aside each month.
Tax Year 2026-27 Sole traders · Income Tax, Class 4 and Class 2 National Insurance · Rates used
Payments on account
How the bill is worked out
| Item | Amount |
|---|
Rates used · Tax Year 2026-27
| Band | Taxable income | Rate |
|---|---|---|
| Personal Allowance | up to £12,570 | 0% |
| Basic rate | £12,571 to £50,270 | 20% |
| Higher rate | £50,271 to £125,140 | 40% |
| Additional rate | over £125,140 | 45% |
| Band | Taxable income | Rate |
|---|---|---|
| Personal Allowance | up to £12,570 | 0% |
| Starter rate | £12,571 to £16,537 | 19% |
| Basic rate | £16,538 to £29,526 | 20% |
| Intermediate rate | £29,527 to £43,662 | 21% |
| Higher rate | £43,663 to £75,000 | 42% |
| Advanced rate | £75,001 to £125,140 | 45% |
| Top rate | over £125,140 | 48% |
- Personal Allowance £12,570, reduced by £1 for every £2 of income above £100,000 (nil from £125,140).
- Class 4 National Insurance: 6% on profits from £12,570 to £50,270, 2% above.
- Class 2: treated as paid with profits of £7,105 or more; below that, voluntary at £3.65 a week.
- Trading allowance: up to £1,000 a year instead of expenses.
- Payments on account: two, each half of the Income Tax and Class 4 bill, unless the bill is under £1,000 or more than 80% was paid at source.
Official sources
- GOV.UK: self-employed National Insurance rates
- GOV.UK: Income Tax rates and Personal Allowances
- GOV.UK: Income Tax in Scotland
- GOV.UK: tax-free allowances on property and trading income
- GOV.UK: simplified expenses for vehicles
- GOV.UK: simplified expenses for working from home
- GOV.UK: payments on account
- HMRC: student and postgraduate loans in your tax return
- GOV.UK: rates and thresholds for employers
- GOV.UK: when you need to use Making Tax Digital for Income Tax
Tax rules and rates change. This calculator follows the rules described on this page and may not cover every situation. Check the official source or a qualified tax professional before filing or invoicing.
About the UK Self-Employed Tax Calculator (Income Tax + Class 4 NI)
As a sole trader you pay Income Tax and Class 4 National Insurance on your profits through Self Assessment — there is no employer to take them from your pay. This calculator turns your turnover and expenses into the year’s bill: Income Tax at the England, Wales and Northern Ireland or the Scottish rates, Class 4 at 6% on profits from £12,570 to £50,270 and 2% above, voluntary Class 2 if your profits are low, and student loan repayments.
It also shows whether you must make payments on account — two advance payments towards next year, each half of this year’s bill — and the larger January payment that surprises many people in their first year. Add a job’s pay and the tax already taken through PAYE, use the £1,000 trading allowance instead of expenses, or claim mileage and working from home at HMRC’s flat rates.
How to use it
- Choose where you live: Scotland has its own Income Tax bands; England, Wales and Northern Ireland share the same ones.
- Enter your turnover for the tax year, then either your allowable expenses or the £1,000 trading allowance (whichever is higher). Under expenses you can add business miles and months of working from home at the flat rates.
- If you also have a job or a pension, open “A job, pensions or other income” and enter the gross pay and the tax already paid through PAYE.
- Tick your student loan plans, or voluntary Class 2 if your profits are under £7,105 and you want the year to count for your State Pension.
- Read the bill, what you keep after tax and NI, and the payments on account. The table shows every step; copy it or download a CSV.
Examples
Profit £35,000 · no other income
Income Tax £4,486 + Class 4 £1,345.80 = £5,831.80 · payments on account 2 × £2,915.90
In the first year with payments on account, January brings £5,831.80 plus the first £2,915.90: £8,747.70.
Profit £50,000
Income Tax £8,982.05 + Class 4 £2,245.80 = £11,227.85
£3,000 turnover, trading allowance · PAYE paid £3,486
Profit £2,000 · bill £400 · no payments on account (under £1,000)
10,000 × 55p + 1,000 × 25p
£5,750 of expenses instead of the car’s running costs
National Insurance for the self-employed
- Class 4: 6% on profits from £12,570 to £50,270, 2% on profits above.
- Class 2: with profits of £7,105 or more it is treated as paid, so the year counts for your National Insurance record at no cost. Below that you pay nothing, but you can pay voluntary Class 2 at £3.65 a week to protect your record.
Both are paid through Self Assessment. GOV.UK: self-employed National Insurance rates.
How payments on account work
Payments on account are advance payments towards next year’s bill, including Class 4: two instalments, each normally half of this year’s Income Tax and Class 4 bill, due by 31 January and 31 July. You do not have to make them if the bill was under £1,000, or if more than 80% of your tax was paid at source (for example through PAYE). Student loan repayments, Class 2 and Capital Gains Tax are paid with the January balancing payment and are not part of them. If your income falls, you can ask HMRC to reduce them. GOV.UK: payments on account.
Trading allowance or expenses
The trading allowance lets you deduct up to £1,000 instead of your real expenses. With gross trading income of £1,000 or less you may not need to tell HMRC at all. You cannot use both, and the allowance cannot create a loss. It is not available for income from your employer (or your spouse’s or civil partner’s), from a partnership you or someone connected to you is in, or from a company you or someone connected to you controls. GOV.UK: trading and property allowances.
Simplified expenses
Sole traders can use flat rates instead of working out the business share of some costs: 55p a mile for the first 10,000 business miles in cars and goods vehicles and 25p after, 24p for motorcycles; and £10, £18 or £26 a month for working from home 25–50, 51–100 or 101+ hours a month. Once you use the flat rate for a vehicle you keep using it for that vehicle. GOV.UK: simplified expenses.
Other countries
Self-employed in the United States? The US Self-Employment Tax & Quarterly Estimated Tax Calculator works out self-employment tax and the quarterly estimated payments under IRS rules.
Limitations
- Savings interest, dividends and capital gains have their own allowances and rates and are not included. Use the UK Capital Gains Tax Calculator for gains.
- Losses are shown but not set against other income or carried forward; pension contributions, Gift Aid, Marriage Allowance and the High Income Child Benefit Charge are not included.
- Partnerships, limited companies, landlords’ property income rules and the Class 1 National Insurance on a job are outside this calculator.
- Student loan repayments use all the income you enter (pay from every job, profits, pensions and property). On the return, savings interest and dividends also count when they are over £2,000 (HMRC: student loans in your tax return); this calculator leaves them out.
- Payments on account are worked out from this year’s bill, as HMRC does by default.
Privacy
Everything happens in your browser. What you enter or open here is not uploaded or stored by MySmartCoPilot.
Frequently asked questions
How much tax will I pay on £30,000 of self-employed profit?
In England, Wales or Northern Ireland with no other income: Income Tax £3,486 (20% of the £17,430 above the Personal Allowance) and Class 4 £1,045.80 (6% of the same £17,430), so £4,531.80 in total. In Scotland the Income Tax is £3,451.07.
Why is my first January payment so big?
In the first year with payments on account you pay the whole bill for the year that has ended plus the first payment on account towards the current year — half as much again. From then on, each year’s two payments on account cover most of that year’s bill.
Do I still pay Class 2 National Insurance?
Not if your profits are £7,105 or more: Class 2 is then treated as paid and the year counts for your State Pension. With lower profits you can choose to pay voluntary Class 2 of £3.65 a week.
Should I use the trading allowance or my expenses?
Whichever is larger. With £600 of expenses on £3,000 of income, the £1,000 allowance taxes you on £2,000 instead of £2,400. With £1,500 of expenses, deducting them is better. You cannot do both.
Do I pay student loan through Self Assessment?
Yes. HMRC works out the repayment on your income for the year — 9% above your plan’s yearly threshold, 6% for a Postgraduate Loan — and adds it to your bill, minus anything an employer already deducted. The UK Student Loan Repayment Calculator shows the plans and thresholds.
When is Self Assessment due?
For the tax year that ended on 5 April, online returns and payment are due by 31 January. The second payment on account is due by 31 July.