Tax Guide for Self-Employed People — UK Expert Guide 2026

Tax can be confusing for self-employed people, but understanding your obligations could save you significant amounts. This guide explains everything you need to know about tax as a self-employed people.

Key takeaways
  • File by 31 January even if you can't pay — Time to Pay spreads bills; late filing compounds penalties
  • Claim the small reliefs — they stack to hundreds per year
  • Pension contributions near £60k/£100k thresholds carry outsized value
  • Check your tax code after any job or benefit change — millions are wrong each year

What Actually Moves the Needle

The UK tax system quietly rewards paperwork: Marriage Allowance (up to £252/year, backdatable four years), uniform and mileage relief, professional-fee deductions — each takes minutes and most eligible people never claim.

Engagement beats avoidance with HMRC: Time to Pay arrangements spread bills over months with modest interest, while silence triggers automatic escalating penalties.

Tax bands create cliff edges worth planning around: crossing £60,000 tapers Child Benefit; £100,000 withdraws the personal allowance at an effective 60% rate. Salary sacrifice near a cliff edge is exceptionally efficient.

Tax Obligations for Self-Employed People

TaxRateThresholdDeadline
Income Tax20-45%£12,570 personal allowance31 Jan (self-assessment)
National Insurance8-15.05%£12,570Via PAYE or self-assessment
Capital Gains Tax10-28%£3,000 annual exemption31 Jan
VAT20%£90,000 turnoverQuarterly

Tax Allowances for Self-Employed People

  • Personal Allowance — £12,570 tax-free income per year
  • Marriage Allowance — transfer £1,260 of allowance to partner
  • Trading Allowance — £1,000 tax-free for self-employed income
  • Property Allowance — £1,000 tax-free for rental income
  • ISA Allowance — £20,000 per year tax-free savings/investment
  • Pension contributions — tax relief at your highest rate
HMRC Tip: Use HMRC's free online tools at GOV.UK to check your tax code, estimate your tax bill, or submit a self-assessment return. You should never need to pay someone to use HMRC's basic services.

FAQs

What expenses can I claim as self-employed?

Anything used solely for business: equipment, travel, a proportion of home costs, software and professional fees. The £1,000 trading allowance can replace itemised expenses for small side incomes.

What happens if I miss the filing deadline?

An automatic £100 penalty, then daily fines after 3 months. File even if you can't pay — payment plans (Time to Pay) stop the worst penalties.

Do I need to file a Self Assessment return?

You must file if you're self-employed with income over £1,000, earn over £150,000, have significant untaxed income, or earn over £60,000 while claiming Child Benefit. The deadline is 31 January online.

Can I reduce tax legally?

Yes — pension contributions, ISAs, salary sacrifice, marriage allowance and Gift Aid are all HMRC-approved routes. Marriage Allowance alone is worth up to £252 a year and is widely missed.

How do I know my tax code is right?

Check the code on your payslip against GOV.UK's checker. Millions of codes are wrong each year — a wrong code means silent over- or under-payment.

Recommended Providers

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HMRC

Official HMRC self-assessment portal.

Go to HMRC

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