Form 1040: the return every US person files, wherever they live.
Form 1040 is the individual income tax return for US citizens and residents. Filing it from abroad does not make it optional or simpler — it adds exclusions, credits and information returns that a domestic preparer rarely handles.
Figures on this page are stated for tax year 2025/26 UK · 2025 US. Thresholds change annually.
One return, worldwide income
The 1040 reports your worldwide income: UK salary, self-employment, rental profit, dividends, interest and gains, all converted to dollars. The filing thresholds are low — roughly the standard deduction, or just $400 of self-employment income — so most working adults abroad cross them.
The reliefs that stop you paying twice sit on top: Form 2555 for the Foreign Earned Income Exclusion, Form 1116 for foreign tax credits, and Form 8833 where a treaty position overrides the default rule.
- Schedules 1, 2 and 3 for additional income, taxes and credits
- Schedule B for foreign accounts, Schedule D and Form 8949 for gains
- Schedule C for self-employment, Schedule E for rental property
The forms that travel with it
A cross-border 1040 rarely stands alone. Non-US accounts bring the FBAR and often Form 8938; UK funds bring Form 8621; a company brings Form 5471; a trust or a large gift brings Form 3520. Each carries its own penalty for silence, independent of any tax due.
We prepare the return and its attachments as a single position, then reconcile the figures against your UK Self Assessment so both authorities see consistent numbers.
Questions we get about this
Yes. The obligation is triggered by income above the threshold, not by tax being due, and the reliefs that reduce the bill to nothing only apply if they are claimed on a filed return.
Filing also starts the clock on the statute of limitations, which is worth having run.
Payment is due 15 April. Taxpayers living abroad get an automatic extension to 15 June to file, and can extend to 15 October on request.
Interest still accrues from April on anything unpaid, so an extension to file is not an extension to pay.
Consumer software handles the domestic 1040 well, but most packages struggle with PFICs, treaty positions and the interaction between the exclusion and foreign tax credits.
The common outcome is a filed return that is technically wrong in an expensive direction, usually on the investment forms.
You can file separately and leave your spouse outside the US system, or elect to treat them as a resident and file jointly - which pulls their worldwide income onto the return.
Joint filing sometimes wins on rates, but it rarely wins once the spouse has significant non-US income or investments. It is worth modelling before the first election.
Last reviewed · Figures stated for tax year 2025/26 UK · 2025 US. Thresholds and rates change annually — check figures against the current tax year before relying on them.
Not sure how this applies to you?
Describe your situation and we will tell you which forms are actually required, with a fixed fee to prepare them.