2026/2027 US & UK Tax Dates and Deadlines for the 2025 Tax Year

Understanding the US Tax Year

The US tax year for individuals runs from January 1 to December 31. For the 2025 tax year, taxpayers in the US and abroad must follow key filing and payment deadlines throughout 2026 and early 2027. Missing these dates may result in penalties and interest, so planning ahead is essential. This guide outlines the major US tax deadlines for individuals, partnerships, corporations, and trusts, as well as estimated tax dates, FBAR requirements, UK deadlines for expats, and the important 65-day election for trusts. It should be noted that entities can also work on a fiscal year basis rather than calendar year, and as such can have different filing dates. The below focuses on calendar year filers, if you have any questions regarding your filing dates, please do get in touch.  

Key US Tax Deadlines for the 2025 Tax Year (Filed in 2026)

Key Deadlines for Individuals

There are many deadlines falling throughout the tax year, and here are some of the main deadlines to consider.

• April 15, 2026 – Deadline to file Form 1040/1040NR (the basic income tax return) for the 2025 tax year and pay any remaining 2025 tax liability. This is also the filing deadline for Form 709 (Gift Tax Return) and Form 3520, annual Return To Report Transactions With Foreign Trusts and Receipt of Certain Foreign Gifts. Extensions are available.
• April 15, 2026 – Deadline to file FBAR (FinCEN Form 114) (report on foreign bank and financial accounts). An automatic extension applies to October 15, 2026.
• June 15, 2026 – Automatic two-month filing extension for US persons living abroad.
• October 15, 2026 – Final deadline for individuals who reside within the US and for FinCEN Form 114 and Forms 3520. 
• December 15, 2026 – Final extended deadline for individuals living outside the US who requested an additional two-month discretionary extension.

Key Deadlines for Businesses and Trusts

Here are some of the main deadlines to plan for:

• March 16, 2026 – Deadline for S Corporations (Form 1120-S) and Partnerships (Form 1065). This date also applies to Form 3520-A (Annual Return of Foreign Trusts with a US Owner).
• April 15, 2026 – Deadline for C Corporations (Form 1120) and US Trusts (Form 1041).
• September 15, 2026 – Final extended deadline for S Corporations and Partnerships that filed extension requests. It is also the final deadline for Form 3520-A. 
• September 30, 2026 – Final extended deadline for US Trusts (Form 1041).
• October 15, 2026 – Final extended deadline for C Corporations.

Understanding the 65-Day election for Trusts

The 65-day election allows trustees to make distributions within the first 65 days of the new tax year and elect to treat the distribution(s) as if made on the final day of the previous tax year. For the 2025 tax year, the 65-day period to make the distributions by is March 6, 2026.

This rule may help reduce overall tax liability by shifting income to beneficiaries in lower tax brackets. The election must be made by April 15, 2026.

Estimated Tax Payment Deadlines for 2026

• January 15, 2026 – Q4 2025 
• April 15, 2026 – Q1 2026 
• June 15, 2026 – Q2 2026 
• September 15, 2026 – Q3 2026 
• January 15, 2027 – Q4 2026 

Other Important US Deadlines

• Estate Tax Returns (Forms 706/706-NA) – Due nine months after the date of death. Extensions are available.
• Forms 5471 (Information Return of US persons with Respect to certain Foreign Corporations), Forms 8621 (Information Return by a Shareholder of a Passive Foreign Investment Company or Qualified Electing Fund), and Form 8938, (Statement of Specified Foreign Financial Assets) will also need to be considered as part of an individual’s US Tax filings. 

Important UK Tax Deadlines 

• January 31, 2026 – Deadline for filing 2024/25 UK Self-Assessment tax returns and making balancing payments. First payment on account for 2025/26 is also due.
• April 5, 2026 – Final day of the 2025/26 UK tax year.
• July 31, 2026 – Second payment on account for 2025/26.
• December 30, 2026 – Deadline to file UK tax returns electronically if opting for PAYE coding adjustments (liability under £3,000).

Year-End Tax Planning Reminder

The 2026 US tax year ends on December 31, 2026. Taxpayers should consider year-end planning strategies, including charitable contributions, retirement contributions, UK foreign tax credit planning, and estimated state tax payments.

Need Help Navigating US/UK Tax Deadlines?

Managing cross-border tax obligations can be complex. Our team at USTAXFS supports US taxpayers, expats, trusts, and businesses with strategic planning and full compliance.

Contact us to book a confidential, introductory call with one of our experts.

In the meantime, stay on top of key US/UK tax deadlines throughout the year with our interactive calendar here.

Article written by Glenn Snow & Shada Robati