The latest deadlines to file taxes vary depending on the country and whether extensions are filed:
United States (for tax year 2024, filing in 2025)
- Regular tax filing deadline: April 15, 2025
- Automatic expat extension if living abroad on April 15: June 15, 2025
- Extended filing deadline if Form 4868 is filed before June 15: October 15, 2025
- Final extension (special circumstances only): December 15, 2025
- Note: Taxes owed must still be paid by April 15, 2025, to avoid interest even if filing is later with extension.
United Kingdom (for tax year ending April 5, 2025)
- Paper tax returns must be submitted by October 31, 2025
- Online tax returns must be submitted by January 31, 2026
- Any tax due for the 2024/25 tax year must also be paid by January 31, 2026
- Registration for Self Assessment must be done by October 5, 2025
- It is possible to submit the tax return anytime after April 6, 2025, but no later than the deadlines above.
So, the absolute latest to file and pay taxes without penalty is:
- U.S.: October 15, 2025 (with extension) for filing, April 15, 2025 for payment
- U.K.: January 31, 2026 for online filing and payment
If filing late in the U.S., penalties and interest may apply unless special extensions are granted; in the U.K. late filing penalties apply after January 31. Let me know if you want details for a specific country or any other tax- related deadlines.
