Self-Employed Tax Calculator UK 2025/26
This self-employed tax calculator estimates your income tax, Class 4 National Insurance and student loan repayments for the 2025/26 tax year. If you work as a sole trader, freelancer or contractor, enter your annual turnover and allowable expenses to see your total tax bill and how much you should set aside each month. The calculator uses current HMRC rates including the £12,570 personal allowance, all income tax bands and the Class 4 NI thresholds. It also shows your effective tax rate and monthly set-aside amount, helping you avoid a surprise bill when your self-assessment return is due in January. Whether you are newly self-employed or reviewing your finances mid-year, this tool gives you a clear estimate in seconds.
Understanding Your Self-Employed Tax Bill
As a self-employed person in the UK, you pay income tax on your taxable profit, which is your turnover minus allowable business expenses. The personal allowance of £12,570 is deducted first, and remaining profit is taxed at 20%, 40% or 45% depending on the band. On top of income tax, you pay Class 4 National Insurance at 6% on profits between £12,570 and £50,270, and 2% above that. Class 2 NI has been effectively abolished from April 2024. If your total tax bill exceeds £1,000, HMRC will require payments on account, meaning you pay half your estimated bill in advance on 31 January and 31 July.
Self-Assessment Deadlines and Payments on Account
The self-assessment tax return for 2025/26 must be filed online by 31 January 2027. Late filing triggers an automatic £100 penalty, and further penalties accrue after three and six months. If you owe more than £1,000 and less than 80% was collected at source, HMRC will set up payments on account for the following year. You can reduce these payments if you expect your income to drop. Full details on deadlines and penalties are available on the GOV.UK self-assessment page.
Reducing Your Self-Employed Tax Bill
Claiming all allowable expenses is the most direct way to reduce your tax liability. Common deductions include office costs, travel between business locations, professional subscriptions, insurance premiums and accountancy fees. If you work from home, you can use HMRC's simplified expenses method to claim a flat rate based on the hours you work. Pension contributions also reduce your taxable profit, so use our pension tax relief calculator to see how much you could save. If you drive for business, our mileage expense calculator shows the tax-free amount you can claim using HMRC approved rates.
Allowable expenses that are wholly and exclusively for your business including office costs, travel, stock, marketing, professional subscriptions and accountancy fees.
The online filing deadline is 31 January following the end of the tax year. For 2025/26 the deadline is 31 January 2027. Late filing incurs an automatic £100 penalty.
An advance payment towards your next tax bill. If your bill exceeds £1,000, HMRC requires two payments on account due 31 January and 31 July.
There is no legal requirement. However an accountant can help identify expenses, ensure correct reliefs and avoid costly mistakes.
The trading allowance lets you earn up to £1,000 from self-employment without paying tax. Above £1,000 you can deduct the allowance instead of actual expenses.
This calculator provides estimates for guidance only. Results use 2025/26 HMRC rates. This is not financial, legal or professional advice. For regulated financial advice, speak to a qualified financial adviser.