When a US citizen dies while living in Britain, the executor inherits two filing systems. In the US that means a final Form 1040 running from 1 January to the date of death, plus any earlier year still unfiled. In the UK it means whatever return HMRC asks for, plus inheritance tax if due. The grant of probate is the document that links the two, and on the US side it also decides how a refund is claimed.
This post is for a British son, daughter, friend or solicitor who has never seen a US return and has just found out the person they are acting for had one. It extends our guide to US and UK tax returns for Americans in the UK with the working order of the job, who signs, the refund route and the short final period. Estate tax and the treaty get a brief mention only, because other posts deal with them.
What does a UK executor have to file for a US citizen
A final Form 1040 for the year of death, a regular return for any earlier year left unfiled, and the UK returns HMRC requests. Income after death belongs to the estate and is reported separately on each side. Publication 559 makes no exception for a representative who lives abroad.
IRS Publication 559 (opens the official IRS page in a new tab) defines a personal representative as an executor, an administrator or anyone in charge of the decedent's property, and says that person must file the final return. It is due when the return would have been due had the death not occurred, which for the year of death means 15 April of the following year. An earlier year that closed before the death is treated differently: it is a regular return, not the final one, and the representative must still file it.
The IRS page on final returns of a deceased person (opens the official IRS page in a new tab) adds that returns for earlier years may have to be filed if they were never made. Publication 559 also confirms that a representative may obtain a filing extension. It does not say whether the automatic move to 15 June for taxpayers abroad (opens the official IRS page in a new tab) survives a death, because that rule looks at where the person is living on the due date. We plan around 15 April or an extension request, and interest runs from 15 April either way.
In what order should the US and UK steps be done
Start in the UK, because the grant of probate and the UK tax figures both feed the US return. Tell HMRC about the death, deal with inheritance tax and the grant, settle the UK income returns, then finish the US years. The estate's own income and any clearance requests come last.
The sequence below is our own working order, not an official one, and the facts can change it. A US filing date arriving before the grant is the usual reason to reorder. The general question of which return comes first has the same answer in most years, for the same reason: the foreign tax credit depends on the UK number. Hold back funds from beneficiaries until the US position is known, because unfiled years can surface late.
- Tell HMRC through Tell Us Once or the HMRC bereavement service (opens the official HMRC page in a new tab)
- Find the Social Security number, past US returns and any IRS letters
- Make the inheritance tax payment needed before the grant (opens the official GOV.UK page in a new tab), then obtain the grant
- File Form 56 with the IRS once the details, including any estate EIN, are ready
- Complete the UK returns HMRC issues, and record tax by period
- File unfiled earlier US years, then the final Form 1040 with the court certificate
Who signs the final Form 1040 and how is it marked
The appointed personal representative signs. If nobody has been appointed and there is no surviving spouse, the person in charge of the property signs as personal representative. The return is marked as a deceased taxpayer's, with the date of death, and it otherwise follows the normal form.
Publication 559 tells the filer to write DECEASED, the name and the date of death across the top. The current Form 1040 instructions ask for the deceased box at the top of page one to be checked and the date entered, and warn that leaving this out may delay processing. Income is reported only up to the date of death, and tax withheld and estimated payments are claimed as credits.
A surviving spouse changes the signature block only where a joint return is possible. Publication 559 lets the survivor alone file jointly if no representative has been appointed before the due date, and bars it if the survivor remarries before the year ends. Most Americans here married to a non-US spouse file separately, as our post on filing status with a non-US spouse explains. Publication 54 says that a spouse's death ends any election to be treated as joint filers for later years.
How is a refund claimed for someone who has died
Usually by attaching the court certificate to the original return, with no separate claim form. An appointed representative filing an original Form 1040 with that certificate does not file Form 1310. Everyone else claiming a refund for the decedent generally does, apart from a surviving spouse on a joint return.
Form 1310 (opens the official IRS page in a new tab) defines a personal representative as an executor or administrator appointed or certified by the court, and it says a copy of the will is not accepted as evidence. The form does not mention foreign courts. A sealed copy of the English grant is the natural document to send as the court certificate, though it may be queried, since the IRS text is silent on the point.
The route matters to a British executor for a practical reason. Form 1310 has a box for the claimant's Social Security number, and its notice says the number is required. Part II also asks about paying out under the law of the state where the decedent was legal resident, which reads awkwardly for an English estate. Attaching the certificate to the original return avoids both questions. An amended claim on Form 1040-X does not: line B of Form 1310 then applies, certificate included.
Earlier years have their own time limit. The general refund period is three years from filing or two years from payment, whichever is later, so a refund on an old unfiled year can be lost by waiting. How the money reaches the estate is a separate problem, since refunds now go to accounts in the taxpayer's name, and we have not found IRS guidance applying that rule to a UK estate. Raise it before filing.
How the short final period works for a Manchester engineer
Take a divorced US citizen employed in Manchester who dies on 14 September 2026, with a British daughter as executor. His final Form 1040 covers 257 days. Those days straddle two UK tax years, so no single UK figure matches the US period, and the 2025 US return is still open as well.
He had extended his 2025 return to 15 October and dies a month before that date. The year closed before his death, so the daughter files it as a regular return, signing as the person in charge of his property if the grant has not yet been issued. Of the 257 days, 95 fall in the UK year ending 5 April 2026 and 162 fall in the UK year he died in. Payslips and the P45 let her split PAYE across those two blocks, which is what Form 1116 needs.
Timing is the hard part. Publication 514 says a cash-method filer takes the credit when tax is paid, while foreign tax generally accrues on the last day of the foreign tax year. PAYE deducted before the death is simple. A UK balance settled months later by the executor is less so, and neither Publication 514 (opens the official IRS page in a new tab) nor Publication 559 answers it directly for a final return. Publication 559 addresses only a beneficiary who pays foreign tax on income in respect of a decedent. This point needs a preparer's judgement, and our individual tax returns work deals with it on the facts.
What does HMRC need from the executor
Notice of the death, then whichever return HMRC decides is needed. HMRC tells the representative if a Self Assessment return is required for income before death, and sends the form. It must arrive by the date in HMRC's letter, which may differ from the usual online deadline. Estate income may need a separate return.
GOV.UK's page on returns for someone who has died (opens the official GOV.UK page in a new tab) says the form goes by post and lists the records usually needed, such as bank statements, the P45, the P60 and pension statements. HMRC's Self Assessment manual treats these as paper cases and says any agent needs a new authority from the representative, because the one signed by the deceased no longer works. The form is the same SA100 family used in life, completed for the period up to the death.
The HS282 helpsheet (opens the official HMRC page in a new tab) says there is no capital gains tax charge on the death itself and that a legatee generally takes assets at market value on that date. Gains on assets the executors sell during administration fall on them. Our UK Self Assessment service prepares the pre-death return alongside the US year so that the same split of dates is used on both.
Where estate tax, estate income and accounts fit
After the income returns, though the checks should start early. Estate tax can apply to a US citizen wherever they lived, estate income has its own return, and foreign accounts have separate rules.
The IRS page on estate tax (opens the official IRS page in a new tab) sets a filing threshold for the year of death, and the UK charges 40% above the available nil-rate bands, with payment due by the end of the sixth month after the death. Our post on the US-UK estate tax treaty deals with which country gives way, and our trusts and estates division reviews the two together. Publication 559 requires Form 1041 from a domestic estate above a modest gross income level, and the Form 1040-NR instructions cover a nonresident alien estate. Which applies to an estate run from England depends on the facts.
Foreign accounts need their own review. The FBAR goes to FinCEN and never with the return. We could not find official guidance setting out who reports a decedent's accounts for the final year, so take advice before assuming nothing is owed. An executor who is a US person has a separate question, covered in our post on the FBAR and inherited accounts. Unfiled earlier years may also bring in the IRS Streamlined filing question, which should be reviewed before filing several years at once. The guide for Americans in the UK sets out the normal annual cycle, which is the record you will be reconstructing.
General information, not advice. The right answer depends on your circumstances and the tax year concerned.
