Self-Employed Tax Calculator UK

As a self-employed person in the UK (2025/26), you pay Income Tax on profits above your £12,570 Personal Allowance at rates of 20% (Basic rate), 40% (Higher rate on income £50,271–£125,140), and 45% (Additional rate above £125,140). You also pay Class 2 NI (£3.45/week if profits exceed £12,570) and Class 4 NI (6% on profits between £12,570–£50,270, plus 2% above £50,270).

For the 2025/26 tax year (6 April 2025 – 5 April 2026), the paper filing deadline is 31 October 2026 and the online filing deadline is 31 January 2027. You must also pay any tax owed by 31 January 2027. If your bill is over £1,000, you may need to make Payments on Account (due 31 January and 31 July).

Common allowable expenses include: office supplies, phone/internet bills, travel costs, professional subscriptions, software/tools, marketing costs, accountancy fees, insurance, and use-of-home costs. You can use simplified expenses (flat rate) for working from home (£6/week without evidence, or £26/month for 25-50 hours). All expenses must be "wholly and exclusively" for business.

Yes — you must register with HMRC for Self Assessment by 5 October following the end of the tax year in which you became self-employed. You can register online at gov.uk. You'll receive a Unique Taxpayer Reference (UTR) number within 10 days (21 if abroad).

Turnover (revenue) is your total business income before any deductions. Profit is what's left after deducting allowable business expenses. You pay tax on your profit, not your turnover. This is why tracking expenses carefully can significantly reduce your tax bill.