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United Kingdom tax deadlines
Seeded deadline records for United Kingdom. The calendar schema is designed to expand into country, year, month, and export views.
Country
United Kingdom
Seed deadlines
2
hmrc · registration
Register for Self Assessment if you need to send a return for the 2025-2026 UK tax year and have not sent one before.
HMRC says late registrants are sent a different filing deadline, generally 3 months from the date on the letter or email.
Extension available: No
October 5, 2026
hmrc · return-filing
Online filing and general payment deadline for the 2025-2026 Self Assessment tax year.
Late filing starts with a £100 penalty and can escalate after 3, 6, and 12 months.
Extension available: No
January 31, 2027
Primary sources
- Check how to register for Self AssessmentVerified 2026-05-01
- HMRC Self Assessment legal frameworkVerified 2026-05-01
- Self Assessment tax returns: penaltiesVerified 2026-05-01
Important disclaimer
This library is for general tax education only. Always verify filing obligations, due dates, and tax consequences against the cited primary source or with a qualified tax professional.