US and UK tax deadlines for Americans in the UK: the full annual cycle

Americans in the UK run two tax calendars that do not line up. The US year is the calendar year and its deadlines fall in spring and autumn; the UK year ends on 5 April and its main deadline is 31 January. The live calendar applies weekend and holiday shifts automatically; this article explains what each date means.

The US cycle

15 January — fourth estimated payment for the year just ended, for people with US tax not covered by withholding or credits.

15 April — payment date, FBAR date, IRA date. The regular due date for Form 1040. Even though most people abroad file later, interest on any tax owed runs from this date, and IRA contributions for the previous year must be made by it. The FBAR for the previous calendar year is also due now, with an automatic extension to 15 October. First estimated payment for the current year.

15 June — automatic two-month extension. If you live outside the US on 15 April you may file by 15 June without asking, attaching a statement that you qualify. It extends the time to file, not to pay. If you need longer, file Form 4868 by this date. Second estimated payment.

15 September — third estimated payment.

15 October — extended return and FBAR. Final date for Form 1040 under a Form 4868 extension, and the end of the automatic FBAR extension. No further FBAR extension exists.

15 December — discretionary extension. Taxpayers abroad who already have the October extension can request a further two months by letter to the IRS. It is granted at the IRS's discretion and does not cover the FBAR.

When any of these falls on a Saturday, Sunday or legal holiday (including Emancipation Day in the District of Columbia on 16 April), the deadline moves to the next business day. HMRC dates do not move.

Information returns

• Form 5471 (UK company owned by US persons) and Form 8865 (UK LLP or partnership): due with the Form 1040, including extensions. Penalties start at US$10,000 per form.
• Form 3520 (gifts or inheritances from non-US persons above the thresholds, and transactions with foreign trusts): due on the same date as your income tax return, including extensions. Penalties can reach 35% of the amount involved.
• Form 8938: part of the return itself.

The UK cycle

• 5 April — tax year ends; 6 April — new tax year begins.
• 31 July — second payment on account for the year just ended.
• 5 October — register for Self Assessment if you need to file for the year ended the previous April and have not filed before.
• 31 October — paper return deadline.
• 31 January — online return, balancing payment and first payment on account for the current year.
• 60 days from completion — report and pay capital gains tax on a UK residential property disposal with tax due.

The dates for the current cycle

Date	What
15 January 2027 (Friday)	Q4 2026 estimated payment
31 January 2027 (Sunday, no shift)	UK online return and payment, tax year 2025/26
15 April 2027	2026 Form 1040 payment date; FBAR 2026 due (auto-extended); IRA contributions for 2026
15 June 2027	Automatic extension to file for taxpayers abroad; Form 4868 by this date for October
31 July 2027	UK second payment on account, 2026/27
15 October 2027	Extended 2026 Form 1040; final 2026 FBAR date
31 October 2027	UK paper return, 2026/27
31 January 2028	UK online return and payment, 2026/27

For 2026 (covering US tax year 2025 and UK year 2025/26) the pattern was the same: 15 April, 15 June, 15 October 2026 and 31 January 2027.

If a deadline has gone

A late Form 1040 with no tax due carries no failure-to-file penalty, but it should be filed to start the statute of limitations. Late FBARs and information returns are where penalties bite, and the right catch-up route depends on what else was missed. See Streamlined filing.