U.S. Tax Filing for Americans in London

Fixed-fee support for U.S. citizens and Green Card holders in London — UK salary and PAYE, ISAs and SIPPs, City finance equity, FBAR and FATCA reporting.

By Danilson Ramos · Founder, Atamatax

Published June 2026 · Updated August 2026

Part of the United Kingdom desk — every US tax topic for United Kingdom in one place.

Check the common United Kingdom products

Which of these do you hold?

Pick every one that applies. Each gets its own read — what the US sees inside the wrapper, and which form it points at.

Free, no account, nothing you answer leaves this page. Open the full portfolio scanner

Local accounts and wrappers

Stocks & Shares ISA holding fundsSIPP holding fundsNone of these

A screen from the product type. Whether a specific fund is a PFIC turns on its own annual facts; whether a wrapper is a trust or a pension for US purposes turns on its documents.

London is home to one of the largest American communities in the world, spread across the City and Canary Wharf, tech, law, media and academia. Many arrive expecting the UK–U.S. tax treaty to handle everything — but PAYE income, tax-advantaged UK accounts and equity compensation still flow onto a U.S. return, often in ways the treaty does not fully shelter.

Typical situations we see in London

ISAs (cash and stocks-and-shares): tax-free in the UK, but the U.S. generally does not recognise the wrapper, and funds inside can be PFICs.
SIPPs and workplace pensions: UK treatment is favourable, but U.S. and treaty treatment of contributions and growth can differ and may need reporting.
City finance and tech professionals with RSUs, options and bonuses to reconcile across UK and U.S. rules.
UK funds, investment trusts and unit trusts held through a local platform that may be PFICs (Form 8621).
Multiple UK bank and investment accounts that together cross the FBAR threshold.

Moving to London does not switch off U.S. tax filing. ISAs, SIPPs, UK funds and equity compensation can each create U.S. reporting obligations — even when the UK has already taxed the income and little or no U.S. tax is ultimately due.

What to check first

Start with whether your combined non-U.S. accounts crossed $10,000 at any point (FBAR), whether you hold UK or other non-U.S. funds (PFIC), and whether the Foreign Tax Credit or Foreign Earned Income Exclusion fits your situation better. The free Tax Risk Check walks you through it in a couple of minutes.

See the complete UK filing map

The country desk connects PAYE, the ISA and SIPP, UK funds, FBAR, Form 8938 and the US–UK treaty in one place.

US expat taxes in the UK

Authorities cited

IRC §1291 — IRC §1291 — Interest on tax deferral (excess-distribution regime)
IRC §1297 — IRC §1297 — Definition of a passive foreign investment company
IRS Form 8621 — About Form 8621 — Information Return by a Shareholder of a PFIC or QEF
IRS Form 8938 — About Form 8938 — Statement of Specified Foreign Financial Assets
31 CFR §1010.350 — 31 CFR §1010.350 — FBAR (FinCEN Form 114) filing requirement and $10,000 threshold
FinCEN Form 114 (FBAR) — Report of Foreign Bank and Financial Accounts (FBAR)

Primary sources (Cornell Legal Information Institute for the US Code and CFR; IRS.gov for forms, procedures, and treaty documents). This page is general information, not individualized tax or legal advice.

Atamatax provides tax preparation support and educational resources. This website does not constitute legal or tax advice.

Frequently asked questions

Is my ISA a problem for U.S. taxes?#

Often, yes. The U.S. generally does not treat an ISA as tax-free, and a stocks-and-shares ISA can hold investments classed as PFICs, which carry extra reporting. Many Americans in the UK review their ISA holdings carefully. Atamatax provides preparation support; this is not individualized advice.

I have a SIPP or workplace pension in London — how is that handled?#

UK pensions generally receive favourable treatment and the UK–U.S. treaty can help, though the U.S. and treaty treatment of contributions, growth and reporting can be nuanced. It is worth reviewing before filing rather than assuming the treaty covers everything.

Do Americans in London still need to file U.S. taxes?#

In most cases yes — the U.S. taxes citizens and Green Card holders on worldwide income regardless of where they live. Foreign tax credits and exclusions often reduce or eliminate the U.S. tax owed, but reporting (including the FBAR) can still be required.

Does Atamatax work with people based in London?#

Yes. Atamatax provides fixed-fee U.S. tax filing support for U.S. citizens and Green Card holders living abroad, including London. The final quote depends on your documents and tax situation.