Self-Employment

Self-Employment Tax Calculator UK 2025/26

Calculate your self-employment tax, National Insurance, and take-home pay with our free UK calculator. See how much tax you owe as a sole trader or freelancer.

· 5 min read

How Self-Employment Tax Works in the UK

When you work for yourself as a sole trader or freelancer, you are responsible for calculating and paying your own tax through HMRC’s Self Assessment system. There is no employer to deduct tax automatically — it’s entirely on you.

As a self-employed person, you pay three main taxes on your profits:

  1. Income Tax — on your taxable profits above the Personal Allowance
  2. Class 2 National Insurance — a flat weekly amount
  3. Class 4 National Insurance — a percentage of your profits

You may also need to register for VAT if your taxable turnover exceeds £90,000 — see our VAT guide for small businesses for details.

Tax-Free Allowances

Before any tax is applied, you benefit from two key allowances:

  • Personal Allowance — £12,570: The first £12,570 of your taxable profits is completely tax-free. This allowance tapers if your total income exceeds £100,000.
  • Trading Allowance — £1,000: If your total self-employed income is under £1,000, you don’t need to report it or pay tax on it. If your income is above £1,000, you can choose to deduct the Trading Allowance instead of claiming actual expenses — useful if your costs are low.

Income Tax Rates on Self-Employed Profits (2025/26)

Income tax is calculated on your taxable profits — that’s your total income minus allowable expenses and your Personal Allowance. The rates are the same as those for employed workers:

Tax Band Taxable Profit Rate
Personal Allowance Up to £12,570 0%
Basic rate £12,571 – £50,270 20%
Higher rate £50,271 – £125,140 40%
Additional rate Over £125,140 45%

National Insurance for the Self-Employed

On top of income tax, you pay two classes of National Insurance:

Class 2 NI

  • Rate: £3.45 per week (£179.40 per year)
  • Who pays: Self-employed people with profits above £12,570
  • Purpose: Builds your qualifying years for the State Pension and certain benefits

Class 4 NI

Profit Band Rate
Up to £12,570 0%
£12,571 – £50,270 6%
Over £50,270 2%

Class 4 NI is calculated on your annual profits and collected alongside your income tax through Self Assessment. For a deeper look at all NI classes, see our National Insurance guide.

Worked Example: £45,000 Profit

Let’s say you’re a freelance web developer with £45,000 in taxable profit after deducting all allowable expenses. Here’s exactly what you’d owe in 2025/26:

Income Tax

Calculation Amount
Personal Allowance (£12,570 at 0%) £0.00
Basic rate (£45,000 − £12,570 = £32,430 at 20%) £6,486.00
Total Income Tax £6,486.00

National Insurance

Calculation Amount
Class 2 NI (£3.45 × 52 weeks) £179.40
Class 4 NI (£45,000 − £12,570 = £32,430 at 6%) £1,945.80
Total National Insurance £2,125.20

Summary

Item Amount
Gross profit £45,000.00
Income Tax £6,486.00
Class 2 NI £179.40
Class 4 NI £1,945.80
Total tax and NI £8,611.20
Take-home pay £36,388.80

Your effective tax rate is approximately 19.1% — significantly lower than the headline 20% basic rate, thanks to the Personal Allowance.

Payments on Account

If your Self Assessment bill is over £1,000, HMRC requires you to make payments on account — two advance payments towards your next year’s tax bill:

  • 31 January — First payment on account (50% of previous year’s bill) + any balancing payment for the previous year
  • 31 July — Second payment on account (50% of previous year’s bill)

This means in your first year of self-employment, you may face a large January bill covering the full year’s tax plus the first payment on account — effectively 150% of a normal year’s tax.

If your income has dropped, you can apply to reduce your payments on account through your HMRC online account. Be careful though — if you reduce them too much and underpay, HMRC may charge interest.

Self Assessment Deadlines

Missing deadlines costs you money. Keep these dates in mind:

Deadline What
5 October (after the tax year you started) Register for Self Assessment with HMRC
31 October Paper tax return deadline
31 January (following the tax year) Online tax return deadline
31 January Pay your tax bill + first payment on account
31 July Second payment on account

Late filing attracts an automatic £100 penalty, rising to daily penalties after three months. Late payment incurs interest plus surcharges.

Tips to Reduce Your Self-Employment Tax Bill

  1. Claim all allowable expenses — Many self-employed people miss legitimate deductions. Everything from office supplies to professional subscriptions can reduce your taxable profit. Read our allowable expenses guide for a full list.
  2. Make pension contributions — Payments into a personal pension attract tax relief at your marginal rate. A £10,000 contribution effectively costs £8,000 for a basic-rate taxpayer.
  3. Use your Trading Allowance wisely — If your expenses are under £1,000, the Trading Allowance may be more beneficial than itemising costs.
  4. Time your purchases — Buying equipment before the tax year ends (5 April) means you claim the deduction sooner through capital allowances.
  5. Claim loss relief — If you make a loss in any year, you can carry it forward against future profits or set it against other income in the same year.
  6. Consider your structure — At higher profit levels (roughly £40,000–£50,000+), operating as a limited company might be more tax-efficient. See our self-employment tax guide for a comparison.