Self Assessment Tax Estimator 2026/2027
How this Self Assessment estimator works
Self Assessment combines all your income sources into a single tax calculation. Enter any mix of PAYE salary, self-employment profit, dividends, rental income, savings interest or other income — the calculator applies the correct HMRC ordering rules, stacks the sources across the tax bands, and shows the total income tax and National Insurance owed for the year.
Payments on account: HMRC requires most self-employed taxpayers to make two advance payments toward next year's bill — 50% due in January and 50% in July. The estimator shows your projected payments on account alongside the current-year balancing payment so you can plan your cash flow and avoid January surprises.
This is an estimate based on the figures you enter. It does not account for specific reliefs, losses carried forward or adjustments unique to your return. For a final figure, use HMRC's online Self Assessment service or consult a qualified UK accountant.