Self Assessment
Work through the filing conditions, then find registration, deadline and penalty guidance.
Explore Self AssessmentApplicable tax year: 2026/27Last checked:
UK tax tools · independent
A clearer route through your UK tax.
AX Calculators provides UK tax tools and a Self Assessment checker, with the reasons behind each result and links to the guidance used.
Check whether a return is neededChoose your next step
Tools for a specific question.
Tax Code
A tax code checker is planned for a later release.
Calculators
UK tax calculators are planned. No tax amount calculation is available in this release.
Sources you can follow
Every published threshold links to the specific GOV.UK page used for its check.
Reasons beside the result
The checker shows the condition that determines each outcome.
Dates made visible
Each page labels its applicable tax year and source-check date.
Our data sources and checking method explain how conditions, dates and limitations are handled.