Mortgages & Money2 min check

Self-Employed Tax Calculator (2026/27)

Estimate your annual Self Assessment liability — Income Tax plus Class 4 National Insurance — based on your business profit.

Short answer

Sole traders pay Income Tax (20%/40%/45%) and Class 4 NI (6%/2%) on profit above the personal allowance. Class 2 NI is now voluntary. If your bill exceeds £1,000, you also make payments on account.

Step 1 of 10%

Calculation method, coverage and version

Inputs used: Annual turnover (sales), Allowable business expenses, Other taxable income (e.g. PAYE salary).
Calculation approach: The calculator applies the rules and assumptions described in “How it works” to the values you enter. Rounding can cause small differences from an official or provider calculation.
Coverage: Mortgages & Money. UK nations, tax treatment, local rules and provider criteria can differ; check the official sources shown below before acting.
Content version: No page-specific review date is currently published. Treat the result as indicative and verify current rules independently.

Not included unless explicitly requested: personal circumstances not entered, provider discretion, future rule changes, professional fees and case-specific exceptions. Read the full calculator methodology.

Primary sources and official verification

Use these official sources to verify current rules before acting. Coverage and dates can differ across England, Scotland, Wales and Northern Ireland.

See the sitewide source policy.

How it works

Self-employed people pay Income Tax on profit (turnover minus allowable expenses), then Class 4 NI on top. The £1,000 trading allowance can replace expenses if they're tiny. Once your tax bill tops £1,000, HMRC asks for "payments on account" — half your expected next-year bill in January and July.

Worked example

Freelancer: £60,000 turnover, £12,000 expenses → £48,000 profit.

Tax: £7,086 (basic rate on £35,430)
Class 4 NI: £2,124 (6% × £35,430)
Total: £9,210 + £4,605 January payment on account

Who should use this

•Sole traders and freelancers
•Side hustlers earning over £1,000
•Landlords with rental income
•Anyone considering going self-employed

Common mistakes

×Forgetting payments on account double the first January bill
×Missing the trading allowance (£1,000)
×Not claiming home office, mileage, professional fees
×Leaving registration too late (5 Oct deadline)

Frequently asked questions

When is my Self Assessment due?▾

Online return + payment by 31 January after the tax year. Paper returns by 31 October.

What expenses can I claim?▾

Anything 'wholly and exclusively' for business — office costs, travel (not commute), phone, professional subscriptions, insurance, marketing.

Do I need an accountant?▾

Not legally required, but most freelancers earning over £30k find one saves more than they cost. FreeAgent, Xero, QuickBooks are popular DIY tools.

When should I register for VAT?▾

Mandatory once 12-month turnover passes £90,000. Voluntary registration can help if your customers are VAT-registered.

Should I incorporate?▾

Often makes sense above £40–50k profit, depending on dividend strategy. Use our Sole Trader vs Ltd calculator.

What is Making Tax Digital?▾

From April 2026, sole traders/landlords with income over £50k must keep digital records and submit quarterly updates via MTD-compatible software.

Related calculators

Sole Trader vs Ltd →Income Tax →National Insurance →VAT Registration →IR35 Calculator →Dividend Tax →