An American resident in the UK works to two calendars. The US return for a calendar year is due on 15 April, moved automatically to 15 June for people living abroad and to 15 October on request. The UK return for the tax year ended 5 April is due by 31 October on paper or 31 January online. Payment dates, account reports and estimated tax fill the months between.
This article is for US citizens and green card holders who file in both countries and want every date in one place. It builds on the deadlines section of our guide to US and UK tax returns for Americans in the UK, adds the payment dates and the property reporting window, and explains which dates extend the time to file and which also extend the time to pay.
Why the US and UK tax years do not line up
The US taxes individuals on the calendar year. The UK tax year runs from 6 April to 5 April. One US return therefore draws on the last three months of one UK tax year and the first nine months of the next, and no single UK document covers the same period.
The mismatch is a practical problem before it is a technical one. A P60 shows pay and tax for the UK year, not the calendar year, so the US return needs payslips to split the figures at 31 December. UK tax paid through Self Assessment belongs to a UK year but is paid in a later calendar year. Bank interest, dividends and rent each have to be cut twice, once for each country.
The deadlines are offset for the same reason. The US return for a calendar year falls due in the spring and can be extended into the autumn. The UK return for the year that ended in that same spring is not due until the following January. Left to the deadlines alone, the US return is filed before the UK figures it depends on exist in final form.
Every US filing date for an American living in the UK
Four dates govern the US return. It is due on 15 April, the filing date moves to 15 June automatically for those living outside the US, Form 4868 moves it to 15 October, and a further discretionary extension can reach 15 December. The FBAR follows its own rule.
The IRS explains the automatic two-month extension (opens the official IRS page in a new tab) for citizens and residents whose home and main place of work are outside the US. No form is needed, but a statement is attached to the return saying which condition applies. To go beyond 15 June, Form 4868 (opens the official IRS page in a new tab) has to be filed by that date, and our form guide to Form 4868 covers the mechanics. Publication 54 (opens the official IRS page in a new tab) describes the last step, a letter to the IRS sent by 15 October explaining why more time is needed.
The FBAR is filed with FinCEN, not with the tax return, and is due 15 April, extended automatically to 15 October. No request is needed for the later date, as FinCEN's page on reporting foreign bank and financial accounts (opens the official FinCEN page in a new tab) confirms. Form 8938 travels with the return and takes whatever extension the return has. US due dates that fall on a weekend or public holiday move to the next working day, so the exact day can shift from year to year.
Estimated tax applies only to people who expect to owe US tax after credits and withholding. It is paid in four instalments using Form 1040-ES (opens the official IRS page in a new tab). The first two fall on the same days as 15 April and 15 June, the third in the middle of September and the fourth in the middle of the following January. Many Americans in the UK owe nothing after the foreign tax credit and make no estimated payments at all.
Every UK Self Assessment date in the same year
The UK dates follow the tax year that ended on 5 April. New filers register by 5 October. A paper return is due by 31 October and an online return by 31 January, when the balance of tax is also payable. A second payment on account falls on 31 July.
The Self Assessment deadlines (opens the official GOV.UK page in a new tab) are fixed in law and are not extended on request. Payments on account are advance instalments towards the next bill, normally half of the previous year's liability each, and apply where much of the tax is not collected at source. The first is paid with the balancing payment on 31 January and the second on 31 July. A first Self Assessment bill can therefore be one and a half times the tax for the year.
One UK date sits outside the annual cycle. A UK resident who sells UK residential property with capital gains tax to pay must report the disposal and pay the tax within 60 days of completion, under the rules on tax when you sell property (opens the official GOV.UK page in a new tab). The gain is then also entered on the annual return. Our cross-border property service deals with that report and with the US reporting of the same sale. From 6 April 2026, sole traders and landlords above a qualifying income level also send quarterly updates under Making Tax Digital.
The first half of the year, month by month
From January to June the UK closes one year and the US opens its filing season. The UK return and payment come first, the UK tax year ends in early April, and the two main US dates follow by the middle of June.
The list assumes a calendar-year US taxpayer who is resident in the UK and files the UK return online. A person who files on paper, or who has no payments on account or estimated tax, can strike out the lines that do not apply. The property reporting window is left out because it runs from the completion of a sale, not from a fixed day.
- Mid-January: fourth US estimated tax instalment for the previous calendar year, where estimates are due
- 31 January: UK online return for the tax year ended the previous 5 April, the balancing payment and the first payment on account
- 5 April: the UK tax year ends, and the return for it can be filed from the next day
- 15 April: Form 1040 due date, the date from which US interest runs, the nominal FBAR date and the first estimated instalment
- 15 June: automatic US filing date for those living abroad, the last day to file Form 4868 and the second estimated instalment
The second half of the year, month by month
From July to December the UK asks for a payment and a registration, and the US extensions run out. The dates cluster in October, when UK registration, the extended US return, the FBAR and the UK paper return all fall within four weeks.
October is the month that catches people. A first-time UK filer who has spent the summer on an extended US return can miss the UK registration date entirely, because nothing from HMRC prompts it. The US dates in this half are the outer limits of extensions, not targets, and a return finished in the summer leaves October clear. Our article on whether Americans on PAYE need to file Self Assessment explains who has to register.
- 31 July: second UK payment on account
- Mid-September: third US estimated tax instalment
- 5 October: register for Self Assessment for the tax year that ended on 5 April
- 15 October: extended Form 1040 date, the end of the automatic FBAR extension and the last day to request more time by letter
- 31 October: UK paper return
- 15 December: final US filing date where the discretionary extension was requested and not refused
Does a US extension give more time to pay
No. Each US extension moves the filing date and leaves the payment date where it was. Interest runs from 15 April on any unpaid US tax, including during the automatic extension to 15 June and the further extension to 15 October.
For most Americans in the UK the point is academic, because UK tax credited on the US return leaves no balance. It matters in the years when US tax is actually due: income inside an ISA, a gain on a home that exists only in dollars, or UK tax paid in a later year than the income. In those years an estimate of the liability is paid by 15 April even though the return itself is filed months later.
Consider a US citizen employed in Leeds who sells shares held in a stocks and shares ISA in the autumn. The UK charges nothing, so there is no UK tax to credit, and the US taxes the gain. If the gain is large, estimated tax may be due in the January that follows, and the remaining balance is due in April. An extension to file changes neither date.
Which return to prepare first and what to do after a missed date
For a UK resident, the UK figures usually come first. The UK has the first right to tax a UK salary and most other income of its residents, and the US return then claims credit for that tax. Preparing the UK computation soon after 5 April gives the US return final figures before 15 October.
The credit is claimed on Form 1116 and needs the UK tax on each category of income. A UK return left until January forces the US return onto estimates, which then have to be corrected. US-source income runs the other way: the US tax on US dividends or rent is settled first and credited on the UK return. Our individual tax returns and UK Self Assessment services work from one file so that each figure is produced once.
When a date is missed, the response is the same in both countries: file as soon as possible, because the cost grows with time. A late UK return carries an initial penalty of £100 even if no tax is owed, and the penalties (opens the official GOV.UK page in a new tab) increase after three, six and twelve months. The US late-filing penalty is a percentage of the unpaid tax, so it is often nil where credits cover the liability. Information forms and the FBAR are treated separately, and several missed years call for the route in our guide to IRS streamlined filing from the UK. The full framework is in our guide for Americans in the UK.
General information, not advice. The right answer depends on your circumstances and the tax year concerned.
