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UK self-assessment calculator
Estimated liability across income sources.
About this calculator
What it estimates
An estimated UK income tax and Class 4 National Insurance liability on self-employed profit.
Assumptions (UK 2025/26 tax year rates)
- •Income tax bands as for take-home pay
- •Class 4 NI at 6% between £12,570 and £50,270 and 2% above
- •No Class 2 NI, payments on account or other income
Estimates only, for orientation. Rates and thresholds change each tax year and your actual liability depends on facts this tool does not ask for. This is not tax advice.
For US–UK filers
Why your real number differs
Self-employed Americans in the UK file both a UK self-assessment and a US Schedule C. TaxStone prepares both where the case has a US dimension, so the two returns reconcile.