UK Self Assessment 2025-26: dates, forms and what to prepare
If you live in France but have UK income, or live in the UK with French income or property, the 31 January 2027 deadline may apply to you. This page sets out the dates, the forms, and what to have ready.
Clarofisc helps you complete forms and points you to the right ones. We are not an accountant, tax adviser or lawyer, and nothing here is tax advice. Always check your own position on GOV.UK or with a qualified professional.
Key dates for tax year 6 April 2025 to 5 April 2026
- 5 October 2026: Last day to tell HMRC you need to file a return for 2025-26, if you have never filed one before.
- 31 October 2026: Deadline for a paper return.
- 30 December 2026: Online filing by this date lets HMRC collect a small balance through your tax code, if you qualify.
- 31 January 2027: Deadline for filing online and for paying what you owe for 2025-26.
Dates from GOV.UK, checked October 2026.
Who might need to file
- People with income from property, pensions, savings or work outside the UK.
- UK landlords, including non-residents letting UK property.
- The self-employed, and people with other untaxed income above HMRC's thresholds.
HMRC decides who must file. Use their "check if you need to send a tax return" tool on GOV.UK.
Forms people with UK and French income often meet
- SA100: The main return: personal details and the summary of your tax.
- SA102: Employment: pay, tax deducted, benefits.
- SA105: UK property income.
- SA106: Foreign income and gains, including French rent, pensions and interest.
- SA109: Residence, remittance basis and non-residence.
Which pages you need depends on your situation. HMRC's own guidance is the authority.
Free tools
Open the 31 January checklist (printable)See Clarofisc's tools for UK and French forms