Form 1040
IRS, U.S. Individual Income Tax Return
The annual federal return for US citizens, green card holders and US residents, reporting worldwide income wherever the filer lives.
What is Form 1040?
Form 1040 is the return every US citizen and green card holder files on worldwide income, including those who have lived in Britain for decades. It is also the place where most other international forms attach. For a UK resident, the main work is converting UK figures to the US calendar year and claiming relief for tax HMRC has already collected.
How Form 1040 works for someone living in Britain
The US taxes by citizenship, so a move to London changes where the filer lives but not whether Form 1040 is required.
The return is due on 15 April. Anyone living outside the US on that date has until 15 June to file without asking, although interest on unpaid tax still starts from the original date. UK salary, bank interest, dividends and pension income all appear on the form in dollars, translated at a consistent exchange rate.
Relief from double tax is claimed through attachments rather than on the main page. Form 1116 converts UK income tax into a credit against US tax on the same income, and Form 2555 excludes a slice of foreign earnings instead. Schedule B asks, in its final part, whether the filer had an interest in or signature authority over a foreign account, and whether they received a distribution from or were a grantor of a foreign trust. That yes or no answer is often where FBAR problems first come to light.
Filing status drives the arithmetic. A US citizen married to someone who is not a US person normally files as married filing separately, where the filing threshold is $5 of gross income. The couple can instead elect to treat the non-US spouse as resident and file jointly, which gives the $31,500 standard deduction but taxes both spouses on worldwide income. A single filer receives $15,750. The right answer depends on who earns what and where.
At a glance
- The IRS, electronically or on paper
- Filed with
- 15 April, or 15 June if living abroad
- Due
- 15 October with Form 4868
- Extended due date
- $5 of gross income
- Married filing separately threshold
Figures are for the tax year stated in the official instructions linked below.
How we handle it
- Individual Tax Returns
US federal returns for Americans living in the UK and British nationals with US income, prepared with the UK figures in view.
- Cross-Border Tax
US and UK returns prepared together from one set of workpapers, so credits, tax years and exchange rates line up across both.
- Treaty Relief
Claims under the US/UK income tax treaty, with Form 8833 disclosure, residence tie-breaker analysis and reduced withholding on US income.
- IRS Streamlined Filing
Catch-up filing under the IRS Streamlined Filing Compliance Procedures for people whose missed US returns and FBARs were non-wilful.
Where people go wrong
The Form 1040 errors we correct most often.
Who files it
- US citizens resident in the UK, including dual nationals and accidental Americans
- Green card holders, until the card is formally surrendered or treated as abandoned
- People who meet the substantial presence test for the calendar year
- Dual-status filers in the year they arrive in or leave the US
01
Reporting UK income on the April to April year instead of the calendar year
02
Answering no to the foreign account question on Schedule B without checking
03
Assuming PAYE deductions in the UK remove the need to file in the US
04
Electing a joint return without modelling the non-US spouse's income and assets
Why US UK Tax Returns
Every form is prepared against the official instructions, and every position on it is one we can point to in the Code, the treaty or HMRC's guidance.
One File
US and UK returns prepared in the same engagement and reconciled line by line.
Primary Sources
Every position traced to the Code, the treaty, IRS instructions or HMRC guidance.
Scope First
Returns, forms, years and fee agreed in writing before work begins.
The Same People
The team that files this year carries the elections and credits into the next.
Questions we are asked
I earn less than the standard deduction. Can I skip the US return?
Not always. The filing threshold depends on filing status, and a US citizen married to a non-US spouse who files separately must file once gross income reaches $5. Self-employment income has its own low threshold too. Even when no return is strictly required, filing can be worth doing to start the statute of limitations or to carry foreign tax credits forward. The answer turns on status and income type.
Which exchange rate do I use to put my UK pay into dollars?
The IRS accepts a yearly average rate for income received evenly through the year, such as salary. Specific transactions, such as the sale of shares or a property, are usually translated at the rate on the date each leg happened. Whichever approach is used, it should be applied consistently across Form 1040 and its attachments. A few items, such as foreign tax credits on the accrual method, have their own translation rules.
Does filing a Form 1040 also cover my FBAR?
No. The FBAR is a separate report filed electronically with FinCEN, not with the IRS and not as part of the return. Form 1040 only asks, on Schedule B, whether a foreign account exists. Form 8938, by contrast, is attached to the 1040 itself. Many UK residents need all three pieces, and the account lists behind them should match.
Primary sources
What this page says is drawn from the official material below. Read it yourself; we would rather be checked than trusted.
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