Updated April 2026 · Kael Tripton · Finance Guide

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UK Self-Employed Tax Calculator 2026 - What You Owe and When

Being self-employed in the UK means managing your own tax affairs - calculating your taxable profit, paying Income Tax and National Insurance Contributions through Self Assessment, and meeting HMRCs payment deadlines. This guide explains how self-employed tax works in 2026, the key rates, and how to estimate what you owe.

Self-Employed Tax Rates 2025-26

Key rates for 2025-26:

Source: HMRC 2025-26 rates. Always verify current rates at gov.uk/income-tax-rates.

How to Calculate Your Self-Employed Tax

Step 1: Calculate your taxable profit. Total business income minus allowable business expenses equals taxable profit.

Step 2: Deduct the Personal Allowance (12,570 in 2025-26). The first 12,570 of profit is tax-free.

Step 3: Apply Income Tax rates to the remaining profit. Basic rate (20%) applies to the next 37,700 (up to 50,270 total income).

Step 4: Add Class 4 NICs - 6% on profits between 12,570 and 50,270; 2% above 50,270.

Example: 35,000 profit. After Personal Allowance: 22,430 taxable. Income Tax at 20%: 4,486. Class 4 NICs at 6%: 1,346. Total: approximately 5,832.

Self Assessment Deadlines 2026

5 April 2026: End of 2025-26 tax year.

5 October 2026: Deadline to register for Self Assessment if self-employed for the first time in 2025-26.

31 October 2026: Deadline for paper Self Assessment returns.

31 January 2027: Deadline for online Self Assessment returns for 2025-26 AND payment of any tax owed AND first payment on account for 2026-27.

31 July 2027: Second payment on account for 2026-27.

Payments on account: if your Self Assessment tax bill exceeds 1,000, HMRC requires advance payments towards the following years tax - two payments of 50% of the previous years bill, in January and July.

Frequently Asked Questions

What expenses can I claim as self-employed?

Allowable self-employed expenses include: office costs (stationery, phone, broadband); travel costs (fuel, parking, public transport - not commuting); clothing (uniforms and protective clothing only); staff costs; marketing; financial costs (bank charges, accountant fees, business insurance premiums); and use of home as office. Personal and non-business expenses are not deductible.

Do I need an accountant as a self-employed person?

Not legally - you can file your own Self Assessment return online. However, an accountant ensures all allowable expenses are claimed, reduces errors that attract HMRC investigation, and typically saves more in tax than their fee costs. Most self-employed people with profits above 30,000 benefit from using an accountant.

What is the 1,000 trading allowance?

The trading allowance allows individuals with self-employment income of 1,000 or less in a tax year to receive this income tax-free without registering as self-employed or filing a Self Assessment return. If your income exceeds 1,000, you must register.

How do I pay my Self Assessment tax bill?

Online through your HMRC online account, by bank transfer, by debit or credit card via the HMRC website, or by cheque. Set up a Government Gateway account at gov.uk if you have not already done so.

Conclusion

Self-employed tax in the UK combines Income Tax and Class 4 NICs on your business profits above the Personal Allowance of 12,570. Keep thorough expense records, meet Self Assessment deadlines (31 January and 31 July), and consider accounting software to simplify record-keeping. Visit gov.uk/self-assessment-tax-returns for HMRCs official Self Assessment guidance.

Last updated: April 2026. Rate data sourced from HomeOwners Alliance, Rightmove, and lender published rates April 2026. Rates change daily - always verify before applying. For free impartial guidance visit MoneyHelper.