The US Tax Deadline Americans Abroad Must Meet, Alongside UK Dates

US tax deadline Americans abroad: an introduction

The first US tax deadline Americans abroad face each year is 15 April, the date any tax owed is due. If you live in the UK, you then get an automatic extension to 15 June to file. Form 4868 takes you to 15 October, and a letter can ask for 15 December. For the 2026 tax year, those dates fall in 2027, and none lands on a weekend.

This article sets out each date, what it covers and how it sits beside your UK Self Assessment calendar. Our full guide to US and UK tax returns explains how the two returns fit together.

Which US tax deadline Americans abroad start from

The regular due date is the starting point. IRS Publication 54 says the regular due date for Form 1040 is 15 April for calendar-year filers. It adds that a due date on a Saturday, Sunday or legal holiday moves to the next business day. For the 2026 tax year, 15 April 2027 is a Thursday, so it stays put. Therefore, every other date in this article is an extension of that one.

Why the dates need care from the UK

An extension is mostly extra time to file, not extra time to pay. That single point causes most of the problems we see. Furthermore, the UK tax year runs from 6 April to 5 April, so one US return draws on two UK years. As a result, you work to two calendars at once. In practice, the US tax deadline Americans abroad meet often arrives before the UK figures are final.

When is your US tax return due if you live abroad?

Your US return is due on 15 April, but Americans living abroad get an automatic two-month extension to 15 June. You do not need to ask for it, although you must attach a statement. The June date is the US tax deadline Americans abroad most often rely on.

The 15 April payment date

Interest runs from 15 April on any tax you have not paid. The IRS page on the automatic two-month extension says you pay interest on any tax not paid by the regular due date. Consequently, the cheapest course is to estimate your bill and pay it by 15 April 2027, even if you file later. The IRS payments page lists the ways to pay.

The automatic 15 June extension

The automatic extension for Americans abroad is two extra months to file and pay, with no form to send. The Form 4868 instructions confirm that you get the two months without making a request. However, interest is still charged from 15 April. For the 2026 tax year, the extended date is Tuesday 15 June 2027. You attach a statement to the return explaining which situation qualified you.

What counts as living abroad

You qualify if you live outside the United States and Puerto Rico on 15 April. Your main place of business or post of duty must also be outside them. Military or naval service on duty outside the United States qualifies too. Notably, the Form 4868 instructions say a visit to the United States on the due date does not matter. So a London resident visiting Boston at Easter still qualifies. In our experience, most US citizens employed in the UK meet this test easily.

How do you extend beyond June to October or December?

You extend to 15 October by filing Form 4868. After that, a letter sent by 15 October can ask for a discretionary extension to 15 December.

Form 4868 and the October date

Form 4868 is the application for an automatic extension of time to file a US individual return. The IRS Form 4868 page links to the current version. Its instructions say the IRS generally cannot extend beyond six months, which is 15 October for calendar-year filers. From abroad, you file it by 15 June and tick line 8 for four more months. For the 2026 tax year, that gives Friday 15 October 2027. Again, the form extends the time to file, not the time to pay.

The discretionary 15 December letter

The December extension is a further two months that the IRS may grant to taxpayers out of the country. Publication 54 says you send the IRS a letter explaining why you need the extra time. You must send it by 15 October. Moreover, you hear back only if the IRS refuses. Because it is discretionary, we treat 15 December 2027 as a fallback, not a plan. Put simply, the last US tax deadline Americans abroad can reach depends on the IRS saying yes.

Form 2350 for the foreign earned income exclusion

Form 2350 is a separate extension for people waiting to qualify for the foreign earned income exclusion. The IRS Form 2350 page says it is for filers who expect to file Form 2555. They need more time to meet the bona fide residence or physical presence test. Publication 54 says you file it by the due date, which is 15 June for those abroad. Therefore, it suits someone who moved to the UK part way through the year.

Which other US dates sit around the return?

Estimated tax has four dates of its own. In addition, the FBAR has a separate deadline, Form 8938 follows the return, and your state may set different dates.

Estimated tax payments

Estimated tax is tax you pay during the year on income with no US withholding. The 2026 Form 1040-ES sets four dates: 15 April 2026, 15 June 2026, 15 September 2026 and 15 January 2027. It also lets you skip the January payment if you file by 1 February 2027 and pay the whole balance. These instalments are not a US tax deadline Americans abroad can extend by living overseas. However, Publication 54 says you generally need not pay estimated tax if you expect to owe less than $1,000. For many UK employees, credits for UK tax keep the US bill below that.

The FBAR and Form 8938

The FBAR is due on 15 April with an automatic extension to 15 October, wherever you live. It does not get the June or December extensions. Our article on the FBAR deadline explains the dates, and FinCEN's FBAR page links to the form. By contrast, Form 8938 follows your return. The Form 8938 instructions say you attach it to your return and file by the return's due date, including extensions.

State returns may follow different rules

Each state sets its own deadlines, so check the state you still file in. For example, the California Franchise Tax Board gave people abroad on 15 April 2026 until 15 June 2026 to file and pay. It also gave an automatic extension to file until 15 December 2026. Other states set their own rules, so the federal dates are not a safe guide. Accordingly, confirm the state rule each year rather than assuming it matches.

How do the UK Self Assessment dates line up?

The UK return for 2025 to 2026 is due online by 31 January 2027, with the balancing payment the same day. The second payment on account follows on 31 July, and new filers register by 5 October.

Two different tax years

The UK tax year runs from 6 April to 5 April. Your 2026 US return covers January to December 2026. So it draws on two UK years: 2025 to 2026, and 2026 to 2027. Consequently, you need UK figures from two years. According to GOV.UK guidance on P60s, your employer must give you a P60 by 31 May. That is one reason the June date suits people working in the UK.

The October, January and July dates

Self Assessment is HMRC's system for collecting tax that PAYE does not cover. The GOV.UK Self Assessment deadlines page says HMRC must receive a 2025 to 2026 paper return by 31 October 2026. The online return and payment are due by 31 January 2027. Payments on account are advance payments towards your next bill, each half of last year's tax. The GOV.UK payments on account guide says they fall due on 31 January and 31 July. You do not make them if last year's tax was under £1,000, or if you paid more than 80% at source.

Registering and the next UK dates

New filers must register for Self Assessment by 5 October after the tax year ends. For 2026 to 2027, that means registering by 5 October 2027. Paper returns are then due by 31 October 2027, and online returns by 31 January 2028. Note that 31 January 2027 is a Sunday, and GOV.UK gives the date without any weekend shift. Therefore, aim to file and pay by the Friday before. Our article on Self Assessment for Americans in the UK explains who needs to file.

Where the two calendars meet

The US tax deadline Americans abroad meet in June comes well before the UK return for the same months. For instance, your 2026 US return is due by 15 June 2027. Yet the 2026 to 2027 UK return is not due until 31 January 2028. As a result, the US return often uses UK figures worked out ahead of the UK filing. We prepare both from one file, so the numbers agree when the UK return follows.

What happens if you miss a US tax deadline?

Missing the payment date costs interest and may add a late payment penalty. Missing the filing date, including any extension, can add a larger late filing penalty.

Interest and the late payment penalty

Interest runs on unpaid tax from 15 April until you pay, even during the June extension. The Form 4868 instructions set the late payment penalty. It is usually 0.5% of unpaid tax a month, up to 25%. However, they treat you as having reasonable cause during the extension in one case. You must have paid at least 90% of the tax by the due date and pay the rest with the return. Therefore, a good estimate paid on time protects you.

The late filing penalty

The IRS failure-to-file penalty page sets the penalty at 5% of unpaid tax a month, up to 25%. When both penalties apply, the filing penalty is reduced by the payment penalty. Importantly, the penalty is based on tax due. So missing a US tax deadline Americans abroad face may cost little if credits for UK tax cover the bill. Even so, filing on time keeps your records in order and avoids questions later.

When several years are missing

If you have missed more than one year, a single late return rarely solves the problem. The Streamlined Filing Compliance Procedures are for taxpayers whose failures were not wilful. Our article on not having filed US taxes while living in the UK explains the first steps. Note that late FBARs are not a penalty-free route, since the IRS removed its delinquent FBAR procedures in July 2026.

How does a typical year of US and UK dates look?

For most Americans employed in the UK, the year runs from a January UK payment to a June or October US filing. Here is how that works in practice.

An example: Sophie in Bristol

Consider a typical case, which is an illustration rather than a real client. Sophie is a US citizen employed in Bristol, with UK savings and a small US brokerage account. She files a UK return because of her savings and dividends. For 2026, her US tax is likely to be small after credits for UK tax. Still, her US dividends may leave something to pay.

Sophie's US dates

First, Sophie pays an estimate of any US tax by Thursday 15 April 2027, so no interest builds. Her P60 for 2026 to 2027 arrives by 31 May 2027. She then aims for the US tax deadline Americans abroad get automatically, Tuesday 15 June 2027, with the statement attached. If a figure is missing, she files Form 4868 by 15 June instead, ticking line 8, to reach Friday 15 October 2027. Meanwhile, she files her FBAR alongside the return, well before its October date.

Sophie's UK dates

On the UK side, Sophie files her 2025 to 2026 return online and pays the balance before Sunday 31 January 2027. Then she makes her second payment on account by 31 July 2027, if one applies. Finally, her 2026 to 2027 UK return is due by 31 January 2028. Because both returns come from one file, the UK figures in her US return match what she later files with HMRC.

How US UK Tax Experts can help

We prepare US and UK returns and track each US tax deadline Americans abroad must meet. First, we work out any US tax so you can pay by 15 April. Next, we file by the June date, or extend to October where the figures need more time. We also prepare the FBAR and Form 8938 alongside the return.

Our US federal returns service covers the US side, and our UK Self Assessment service covers the UK side. Both come from one file, so the two returns agree.

Conclusion

In summary, the US tax deadline Americans abroad start from is 15 April, when interest begins on unpaid tax. You then have until 15 June automatically, until 15 October with Form 4868, and possibly 15 December by letter. For the 2026 tax year, those dates fall in 2027 and none moves for a weekend. Above all, pay early, keep the FBAR on its own October date, and keep 31 January and 31 July in view for the UK.

Contact us

Want next year's US and UK returns filed on time? Email us at hello@usuktaxexperts.com, or tell us about your situation through our contact page. We reply within one working day with what we would need from you.