Self Assessment Calculator 2026/27
Your self assessment bill includes income tax on profits after the £12,570 allowance, Class 4 NI at 6% and 2%, and any student loan repayments. If the bill exceeds £1,000, HMRC requires payments on account toward next year. Enter your profits below for a full breakdown and payment schedule.
Figures verified against HMRC Income Tax rates on .
Written by James HartleyCIMA
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Your taxable profits after allowable business expenses for the tax year.
Any salary income already taxed via PAYE. Leave as 0 if fully self-employed.
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How Self Assessment Calculator 2026/27 Works
Self-employed individuals pay income tax on profits via self assessment, not PAYE. We calculate tax on your total income (profits + any employment income), then subtract any PAYE already collected to find what's due via your return.
If you claim Child Benefit and the higher earner has adjusted net income above £60,000, you may also owe the High Income Child Benefit Charge. See our Child Benefit UK guide for rates and who should still claim.
Class 4 National Insurance
Unlike employees who pay Class 1 NI, the self-employed pay Class 4 on profits: 6% on profits between £12,570 and £50,270, and 2% above £50,270. This is calculated separately from income tax.
Payments on account
If your bill exceeds £1,000, HMRC requires 50% upfront on 31 January and another 50% on 31 July - based on last year's bill. Any difference is the balancing payment due the following January.
Making Tax Digital, 2026/27
From April 2026, Making Tax Digital for Income Tax begins for self-employed individuals and landlords with gross income over £50,000 (based on 2024/25 tax returns). If you fall into this category, you must keep digital records and submit quarterly updates to HMRC using compatible software. The first quarterly report is due by 7 August 2026.
Frequently Asked Questions
You must file a self assessment return if you: are self-employed with profits over the trading allowance (£1,000); are a company director; have income over £100,000; receive untaxed income (rental, dividends, etc.); are a partner in a business; or have capital gains. HMRC may also ask you to file even if none of these apply.
Payments on account are advance payments toward your next year's tax bill. HMRC requires them if your self assessment bill exceeds £1,000 and less than 80% was collected at source. You pay half on 31 January and half on 31 July. They're based on the previous year's bill, so a rising income means you'll owe a balancing payment the following January.
Class 4 NI is paid by the self-employed on their profits. For 2026/27: 6% on profits between £12,570 and £50,270, and 2% above that. Class 2 is treated as paid when profits reach £7,105; voluntary Class 2 is £3.65/week below that threshold.
Paper returns must be submitted by 31 October following the tax year end. Online returns must be submitted by 31 January. Any tax owed must also be paid by 31 January. A £100 penalty applies immediately if you miss the deadline, with further daily penalties after 3 months.
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Official Rates Used
This calculator uses official HMRC rates for 2026/27. View the current rates at GOV.UK:
Rates last verified:
Disclaimer: This calculator provides estimates based on standard HMRC rates for 2026/27. Results may vary based on individual circumstances. This is not financial advice. Always consult a qualified accountant or CIMA-qualified financial adviser for personal tax matters.