Who has to file
You file an FBAR if you are a US person with a financial interest in, or signature authority over, foreign (non-US) financial accounts whose aggregate value exceeded $10,000 at any time during the calendar year. Two features catch people out. It is an aggregate test, so five accounts holding $3,000 each breach the threshold together even though none does individually. And it is an any-time test, so a one-day spike, for example when a bonus or sale proceeds land briefly in your account, can push you over even if balances are otherwise small. Each account is reported at its maximum value during the year, converted to US dollars.
The trap for Americans in the UK
From the US point of view, your everyday UK banking is "foreign". Current accounts, savings accounts, building society accounts and cash ISAs are all foreign financial accounts for FBAR, and the US does not recognise the ISA wrapper as tax-free. Joint accounts, dormant accounts and accounts you merely have signature authority over are easy to overlook. Penalties are real: the non-wilful penalty has a ceiling of $16,536 per report (assessed on or after 17 January 2025, inflation-adjusted annually), and wilful penalties run far higher. Our guide FBAR and FATCA explained covers the detail, including the separate, higher-threshold FATCA Form 8938.
What to do
Check the high-water value of every non-US account; if the combined total topped $10,000, file FinCEN Form 114 through the BSA E-Filing System by 15 April (automatically extended to 15 October). If you are behind and the failure was non-wilful, the Streamlined Foreign Offshore Procedures typically let you catch up with three years of returns and six years of FBARs with the offshore penalty waived. FBAR and any streamlined submission are US filings, handled by our US partners (Enrolled Agents and CPAs), whom we coordinate for you, while Horizon looks after the UK side, as set out in our guide for Americans living in the UK.