Calculate your income tax, Class 2 NI, and Class 4 NI as a sole trader for 2026-27.
This calculator provides estimates for guidance only. It does not constitute financial or tax advice. Tax rates and NI thresholds may change. Always verify with HMRC or a qualified accountant before making financial decisions.
Being self-employed in the UK means you are responsible for calculating and paying your own tax through HMRC Self Assessment. Unlike employed workers whose tax is deducted at source through PAYE, sole traders must understand three separate tax charges: income tax, Class 2 National Insurance, and Class 4 National Insurance. The Self-Employment Tax Calculator computes all three for the 2026-27 tax year, giving you a complete picture of your tax liability. Income tax for the self-employed works the same way as for employees -- you receive a personal allowance of GBP 12,570 tax-free, then pay 20% basic rate on profits up to GBP 50,270, 40% higher rate up to GBP 125,140, and 45% additional rate above that. However, self-employed National Insurance is calculated differently from employee NI. Class 2 NI is a flat weekly rate of GBP 3.45 (GBP 179.40 per year) payable when profits exceed the Small Profits Threshold of GBP 12,570. Class 4 NI is 6% on profits between GBP 12,570 and GBP 50,270, and 2% on profits above GBP 50,270. Understanding your total tax bill helps you set aside the right amount throughout the year and avoid a nasty surprise at Self Assessment time. HMRC may also require payments on account -- advance payments toward next year's tax bill -- which effectively means you pay 150% of your tax in the first year of self-employment. This calculator helps you plan for these obligations.
To calculate your self-employment taxes: 1. Enter your annual net profit. This is your total business income minus allowable business expenses. If you use the cash basis of accounting, it is the cash received minus cash paid out for business purposes during the tax year (6 April to 5 April). 2. Enter your business expenses (optional). This field is for reference only -- it is not deducted from the profit figure above. Enter the total expenses you have already deducted to arrive at your net profit, for your records. 3. View the results. The calculator shows your income tax, Class 2 NI, Class 4 NI, total tax bill, take-home pay (profit minus total tax), and your effective tax rate. The pie chart breaks down how your profit is split between tax, NI, and take-home pay. 4. Plan your tax payments. Set aside the total tax amount shown, ideally in a separate savings account. Remember that if your tax bill exceeds GBP 1,000, HMRC will require payments on account -- two advance payments of 50% of the previous year's tax bill, due 31 January and 31 July. 5. Experiment with profit levels. If you are planning your business finances, try different profit figures to understand the marginal tax rates at each level. This helps you decide whether additional work is worth the after-tax return. 6. Consider allowable expenses. The lower your net profit, the lower your tax. Ensure you are claiming all allowable expenses including office costs, travel, professional subscriptions, and the trading allowance (GBP 1,000 for very small businesses).
The calculator applies three separate tax charges to your annual net profit: **Income Tax:** - Personal allowance: GBP 12,570 (tax-free) - Basic rate: 20% on profits from GBP 12,570 to GBP 50,270 - Higher rate: 40% on profits from GBP 50,270 to GBP 125,140 - Additional rate: 45% on profits above GBP 125,140 For income over GBP 100,000, the personal allowance tapers at GBP 1 for every GBP 2 over GBP 100,000. **Class 2 NI:** - GBP 3.45 per week (GBP 179.40 per year) if profits are GBP 12,570 or more **Class 4 NI:** - 6% on profits between GBP 12,570 and GBP 50,270 - 2% on profits above GBP 50,270 For example, on GBP 40,000 profit: Income tax = (40,000 - 12,570) x 20% = GBP 5,486.00. Class 2 NI = 52 x GBP 3.45 = GBP 179.40. Class 4 NI = (40,000 - 12,570) x 6% = GBP 1,645.80. Total tax = GBP 7,311.20. Take-home = GBP 32,688.80. Effective rate = 18.3%. On GBP 80,000 profit: Income tax = GBP 7,540 (basic) + GBP 11,892 (higher) = GBP 19,432. Class 4 NI = GBP 2,262 (main) + GBP 594.60 (additional) = GBP 2,856.60. Total tax = GBP 22,468.00.
Self-employed individuals must register with HMRC for Self Assessment and file a tax return by 31 January following the end of the tax year (or 31 October for paper returns). Late filing incurs automatic penalties starting at GBP 100. Allowable business expenses that reduce your taxable profit include: office and premises costs, travel and vehicle expenses (you can use simplified mileage rates of 45p per mile for the first 10,000 miles), staff costs, stock and materials, legal and financial costs, marketing and advertising, and professional subscriptions. You can also claim capital allowances on equipment purchases, including the Annual Investment Allowance of up to GBP 1,000,000. If your annual turnover exceeds GBP 85,000, you must register for VAT and charge VAT on your invoices. The Flat Rate Scheme can simplify VAT accounting for smaller businesses by allowing you to pay a fixed percentage of your turnover. Consider whether it would be more tax-efficient to operate through a limited company rather than as a sole trader. Company directors can take a mix of salary and dividends, which may reduce total tax and NI. However, limited companies have additional compliance costs (annual accounts, confirmation statement, corporation tax return) and the tax advantage narrows at higher profit levels. A qualified accountant can advise on the best structure for your circumstances. Class 2 NI contributions count toward your State Pension entitlement. You need 35 qualifying years of NI contributions to receive the full new State Pension. If your profits fall below the Small Profits Threshold, you can still pay Class 2 NI voluntarily to protect your pension record.