What is payment on account?

If your Self Assessment bill exceeds £1,000, HMRC may require advance payments toward next year's tax — typically half your prior bill twice yearly.

What is the personal allowance?

The personal allowance is income you can earn before paying income tax. It tapers for high earners — the calculator uses standard published thresholds.

Do I need to register as self-employed?

You must register with HMRC if your gross trading income exceeds £1,000 in a tax year or if you need to file for other reasons.

United Kingdom — England, Wales & Northern Ireland · Tax year 2025/26 · Self-employed profits

UK Self-Employed Tax Calculator

Estimate HMRC Self Assessment tax, Class 4 NIC, and payment on account.

Self-employment turnover (£)

Allowable expenses (£)

Other income (£)

Employment, rental, etc.

Net profit

£37,000.00

Income tax

£4,886.00

Class 4 NIC

£1,465.80

Total tax

£6,351.80

Payment on account (est.)

£3,175.90

Effective rate

17.2%

Tax year 2025/26 · England, Wales & NI · Self Assessment estimate

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UK Self Assessment for self-employed income

How Self Assessment works

Self-employed profits are reported on your Self Assessment tax return. Income tax is calculated on profits after allowable expenses, using UK income tax bands. Class 4 National Insurance contributions apply to profits above the lower threshold.

Class 2 NIC was abolished for most self-employed people from April 2024 — this calculator focuses on income tax and Class 4 NIC.

Payment on account

If your bill exceeds £1,000, HMRC may require payments on account — advance payments toward next year's tax based on prior year liability. Budget for January and July payment deadlines.

Allowable expenses must be wholly and exclusively for business purposes. Keep receipts and mileage logs aligned with HMRC guidance.

Frequently asked questions

?Does this include Class 2 National Insurance?: Class 2 NIC was abolished for most self-employed people from April 2024. This calculator includes Class 4 NIC and income tax only.
?What is payment on account?: If your Self Assessment bill exceeds £1,000, HMRC may require advance payments toward next year's tax — typically half your prior bill twice yearly.
?What is the personal allowance?: The personal allowance is income you can earn before paying income tax. It tapers for high earners — the calculator uses standard published thresholds.
?Do I need to register as self-employed?: You must register with HMRC if your gross trading income exceeds £1,000 in a tax year or if you need to file for other reasons.