Self-Employed Tax Calculator
Calculate your self-employed income tax, Class 2 and Class 4 National Insurance for 2026/27. See what you actually keep — and how it compares to being employed.
Your self-employed income
Office costs, travel, materials, professional services, etc.
Self-employed tax explained
As a self-employed sole trader in the UK, you pay tax on your net profit — your total income minus allowable business expenses. The main taxes are:
If your Self Assessment tax bill is over £1,000, HMRC will ask for Payments on Account— two advance payments towards next year's bill (each 50% of the previous year's tax). This means your first year of self-employment can feel expensive: you pay this year's tax andhalf of next year's upfront.
Source: GOV.UK Self-employed NI rates · Register for Self Assessment
Self-employed tax FAQs
How is self-employed tax calculated in the UK?
Self-employed tax is calculated on your net profit (income minus allowable expenses). You pay income tax on profit above your Personal Allowance (£12,570), plus Class 2 NI (£3.45/week) and Class 4 NI (6% on profit between £12,570 and £50,270, then 2% above £50,270).
What is Class 2 National Insurance?
Class 2 NI is a flat-rate weekly contribution of £3.45 (£179/year in 2026/27) paid by self-employed people with profits above the Small Profits Threshold (£6,725). It qualifies you for State Pension and some benefits. It's paid via Self Assessment.
What is Class 4 National Insurance?
Class 4 NI is an earnings-related contribution paid by self-employed people. In 2026/27, you pay 6% on profits between £12,570 and £50,270, and 2% on profits above £50,270. Unlike Class 2, it does not count towards benefit entitlements.
Do self-employed pay more or less tax than employees?
Self-employed people generally pay slightly less NI than employees (6% Class 4 vs 8% employee rate), but they don't get employer pension contributions and must pay their own pension. They also don't get sick pay, holiday pay, or employment rights. The net difference depends on your situation.
When do I need to file a Self Assessment?
You must register for Self Assessment by 5 October following the end of the tax year in which you started trading. The deadline for online Self Assessment returns is 31 January following the end of the tax year. For 2026/27, this is 31 January 2028.
What expenses can I deduct as self-employed?
Common deductible expenses include: office costs (rent, utilities, internet), travel (mileage, public transport for business), stock/materials, marketing, professional services (accountant, insurance), phone bills (business portion), and equipment/tools. You can only deduct expenses 'wholly and exclusively' for business purposes.