Filing a US tax return from the UK

This is the obligation every other tax page on this site assumes. The IRS puts it flatly: the rules for filing income, estate and gift tax returns and paying estimated tax are generally the same whether you are in the United States or abroad, and you are subject to tax on worldwide income from all sources. UK tax already paid on that income does not remove the filing duty. It usually removes the bill, which is a different thing, and only once you have filed.

Who has to file

Whether you file turns on gross income against the threshold for your filing status, not on where the money was earned. For 2025 returns those thresholds are $15,750 filing single under 65, $17,750 filing single at 65 or older, and $31,500 filing jointly with both spouses under 65.

The number that catches people out is married filing separately: $5. An American in the UK married to a British spouse who has no US tax status commonly files separately, and at that threshold the question of whether to file is settled before it is asked. Net earnings from self-employment of $400 require a return on their own, whatever your filing status.

Everyone who files, or who is claimed as a dependant on a return, needs a social security number or an individual taxpayer identification number. The IRS points to Form SS-5 for the first and Form W-7 for the second.

The deadline abroad is June 15

The regular due date is April 15. Living outside the United States earns an automatic two-month extension to June 15, and there is nothing to file to claim it. The extension is narrower than it looks: interest still runs on any tax not paid by April 15, so it buys time to file rather than time to pay.

If June 15 is not enough, Form 4868 filed before that date moves the deadline to October 15. The FBAR, the report of foreign bank and financial accounts, keeps its own calendar and is due April 15 through the BSA e-filing system, so the return and the report are not on the same clock. See the FBAR for what it covers.

Two ways the same income is not taxed twice

The foreign earned income exclusion, claimed on Form 2555, takes earned income off the US return altogether, up to $130,000 for 2025 and $132,900 for 2026. It asks for a tax home in a foreign country plus one of two tests: bona fide residence in a foreign country for an uninterrupted period covering an entire tax year, or physical presence in a foreign country for at least 330 full days in any 12 consecutive months. A separate housing exclusion runs alongside it, limited in general to 30% of the maximum exclusion, which is $39,000 for 2025 and $39,870 for 2026 before the adjustment for where you live.

The foreign tax credit, claimed on Form 1116, works the other way. The income stays on the return and the UK tax you paid on it is credited against the US tax due. Only income, war profits and excess profits taxes qualify. The same taxes can instead be taken as an itemised deduction, though the IRS says that in most cases taking them as a credit is to your advantage.

The word doing the work in the exclusion is earned. Interest, dividends and capital gains sit outside it whatever your salary does, which is why the accounts on this site still matter to a US return after Form 2555 has been filed. Which mechanism fits an actual set of numbers is a question for a cross-border specialist, not a page.

Filing and reporting are different duties

A return reports income. The FBAR and Form 8938 report accounts, and you can owe them in a year you owe no tax at all. They run on their own thresholds, and meeting one says nothing about the other. Filing a return does not discharge them.

The same split explains why a UK product can be tax-efficient and still expensive to hold. An ISA is taxable income on a US return however the UK treats it, and funds inside one are PFICs, passive foreign investment companies, taxed punitively and carrying a reporting form of their own. The treaty protects less than most people expect, because its saving clause lets the US tax its own citizens as if the treaty were not there.

If you have not been filing

There is a defined route back. The streamlined foreign offshore procedures are open to people whose failure to file was not willful, which the IRS defines as conduct due to negligence, inadvertence or mistake, or resulting from a good faith misunderstanding of the law. You meet the residence test if, in one or more of the three most recent years whose due date has passed, you had no US abode and were physically outside the United States for at least 330 full days.

The submission is three years of delinquent or amended returns and six years of delinquent FBARs. The IRS states that returns filed under the procedures are not subject to failure-to-file, failure-to-pay, accuracy-related, information return or FBAR penalties, unless an examination finds fraudulent conduct or a willful FBAR violation. Certifying non-willfulness is a statement with consequences, so it is worth taking to a specialist rather than assessing yourself.

Sources

• IRS, US citizens and resident aliens abroad
• IRS Publication 501, filing thresholds for 2025 returns
• IRS, foreign earned income exclusion
• IRS, figuring the foreign earned income exclusion
• IRS Rev. Proc. 2025-32, 2026 inflation adjustments
• IRS, foreign tax credit
• IRS Publication 590-A, contributions to IRAs
• IRS, streamlined filing compliance procedures
• IRS, US taxpayers residing outside the United States