Accidental American Citizenship Tax Problem: Banks, FATCA Letters and What to Do

The accidental American citizenship tax problem usually arrives as a bank letter: a UK bank has seen a US birthplace in its records and, under FATCA, must ask whether you are a US person. Answer it truthfully, start a Social Security number application if you have never had one, and bring your FBARs and US returns up to date before the IRS asks.

What is the accidental American citizenship tax problem?

The accidental American citizenship tax problem is really two problems that arrive together. The first is a banking problem: your bank has to decide whether to report your account to the United States, and it needs documents from you to do it. The second is a filing problem: if you are a US citizen, the US expects tax returns and foreign account reports from you wherever you live.

The two run on different clocks. The bank wants a reply within weeks. The filing position can take months to put right, largely because a first Social Security number takes time. This article deals with the bank side and the order to do things in. For the underlying rules on who counts as a citizen and what the US asks for, see our guide to accidental American tax and whether you owe the IRS anything.

Why has your UK bank sent a FATCA letter?

Your bank sent the letter because something in its records points to the United States. FATCA, the US Foreign Account Tax Compliance Act, works in the UK through an agreement between the two governments, signed in September 2012. In HMRC's words, the agreement "requires UK financial institutions to report to HMRC on US customers that hold accounts with them". HMRC then exchanges that information with the US.

Banks do not guess. HMRC's International Exchange of Information Manual sets out the indicators, called indicia, that a bank must search its records for. IEIM402780 lists them, and for FATCA they are:

What the bank found	Where it usually comes from
You are identified as a US citizen or resident	An earlier form you completed, or a US passport used as ID
An unambiguous indication of a US place of birth	The birthplace printed in your British or other passport
A current US mailing or residence address	A period living or studying in the US, or a relative's address
A current US telephone number	An old mobile number left on the account
Standing instructions to transfer funds to a US account	Regular payments to family or a US account of your own
A power of attorney or signatory authority held by someone with a US address	A relative in the US named on the account
An "in-care-of" or "hold mail" address in the US as the only address on file	Rare for UK residents

Where a bank finds one of these, the account becomes reportable unless the bank can "cure" the indicator with evidence. That is what the letter is for. It is a due diligence request, and it carries no judgement about whether you have done anything wrong.

What is the bank actually asking you for?

The bank is asking for a self-certification: a signed statement of where you are tax resident and whether you are a US citizen. For new accounts, IEIM403140 says the self-certification must allow the bank to determine the account holder's tax residence and whether they are a US citizen, and must include the account holder's tax identification number. The bank should obtain it within 90 days of the account opening.

If you confirm US citizenship, the number the bank wants is a US taxpayer identification number. IRS Notice 2024-78 states plainly that the US TIN of a US citizen is the individual's Social Security number. Some banks collect it on their own form, and some ask for IRS Form W-9, the standard US form for giving a correct TIN to someone who has to report to the IRS.

Not replying does not make the question go away. HMRC's guidance says that where no valid self-certification is obtained, the account is reportable until one is. Silence means the bank reports what it has, and you lose the chance to put the right facts on the record.

If you are a US citizen

Say so. The self-certification is a formal declaration, and the facts behind it, a birth certificate or a parent's citizenship, do not change because a form says otherwise. Confirming US status leads to reporting, which is uncomfortable if you have never filed, but it is a position you can manage. A false declaration is a separate problem layered on top of the first.

If you were born in the US but are not a US citizen now

A US birthplace can be set aside, but only with specific documents. Under IEIM402880, the bank needs all three of the following:

1. A self-certification that you are neither a US citizen nor a US resident for tax purposes.
2. A non-US passport or other government-issued identification showing citizenship of another country.
3. A copy of your Certificate of Loss of Nationality of the United States, or a reasonable explanation of why you do not have one despite renouncing, or of why you did not obtain US citizenship at birth.

The third item is the one people miss. A British passport by itself does not cure a US birthplace, because most people born in the US are citizens from birth and hold both nationalities. The explanation route exists for narrow cases, such as children born to accredited foreign diplomats.

What happens if you have no Social Security number?

You can still answer the bank, and the bank can still keep the account. This is the point most accidental Americans worry about, and the IRS has addressed it directly. Notice 2024-78 extends earlier relief so that a bank in a country with a FATCA agreement like the UK's will not be treated as significantly non-compliant solely because it fails to report a US TIN on a pre-existing account for calendar years 2025, 2026 and 2027.

The relief comes with conditions, and they explain the letters you receive. For each account without a number, the bank must:

• obtain and report your date of birth;
• ask you for the missing US TIN every year, using the contact method most likely to reach you;
• search its electronic records for the number every year;
• report a code that describes why the number is missing;
• report your UK tax reference if it holds one, and your city and country of residence.

So an annual letter asking for a Social Security number is the bank following the notice, not a sign that the account is about to close. HMRC reflects the same conditions in IEIM402045.

Two limits matter. The relief covers pre-existing accounts, not accounts opened later, which is why opening a new account or moving banks without a number is harder than keeping an old one. And the relief is temporary: the IRS says that any permanent relief is expected to be narrower.

The long-term fix is to get the number. The Social Security Administration's joint FAQ for US citizens abroad explains that a first-time card is applied for through a Federal Benefits Unit at a designated US embassy or consulate, that applicants aged 12 or over who have never had a number must attend an interview in person, and that there is no fee.

Can a UK bank close or refuse your account?

FATCA does not require it. The UK-US agreement asks banks to identify and report US customers; it does not tell them to close the accounts of people who cooperate. Notice 2024-78 goes further and makes the relief conditional on governments encouraging their financial institutions "to not discriminate against U.S. citizens that do provide a U.S. TIN".

In practice some providers, particularly investment platforms and smaller institutions, decide that US customers are not worth the compliance work, and decline new business or ask existing customers to leave. That is a commercial choice, and UK law puts some limits around it:

• Notice and reasons. Under the Payment Services and Payment Accounts (Contract Termination) (Amendment) Regulations 2025, a provider ending an open-ended contract entered into on or after 28 April 2026 must give at least 90 days' notice and explain its reasons in enough detail for the customer to understand them. Older contracts keep the previous minimum of two months. There are exceptions, including where the provider is meeting its obligations under financial crime law.
• Basic bank accounts. Under the Payment Accounts Regulations 2015, the largest UK current account providers are designated to offer basic bank accounts to people who are legally resident in the UK and have no account or do not qualify for a standard one. A refusal must be explained in writing where the law allows.
• Complaints. A closure or refusal can be taken to the provider's complaints process and then to the Financial Ombudsman Service.

The practical point is that a customer who replies, explains and shows progress is in a far stronger position than one who has ignored three letters.

FBAR for accidental Americans: the report behind the bank letter

The FBAR is your side of the same information the bank sends. A US citizen files FinCEN Form 114, the FBAR, for any calendar year in which the combined value of their accounts outside the United States exceeded $10,000 at any time. Current accounts, savings accounts and ISAs all count towards the total. The FBAR is due 15 April following the calendar year reported, with an automatic extension to 15 October, so the FBAR for 2025 is due by 15 October 2026.

Illustrative example: a Bristol teacher born in Texas has a current account that peaked at £4,000 in 2025, a cash ISA holding £3,500 and a joint savings account with her husband holding £6,000. No single account is large, but together they came to £13,500, which is comfortably above $10,000 once converted to dollars. She has an FBAR to file for 2025, listing all three accounts, including the joint one in full.

For years already missed, the IRS guidance on the FBAR page is direct: a late FBAR is a violation that may carry penalties, and someone the IRS has not yet contacted should file late FBARs as soon as possible, with an explanation, to keep potential penalties to a minimum. Records behind each FBAR should generally be kept for five years from its due date. Our walkthrough on filing an FBAR for the first time covers the form itself, and what FBAR reporting is covers the basics.

FBARs are rarely filed in isolation by someone who has never filed a US return. They normally travel with the tax returns under one of the IRS catch-up routes, which is why the order of steps below matters.

What should you do when the letter arrives?

1. Read what is being asked and note the deadline. Banks usually give a date. If you need longer, ask in writing before it passes.
2. Establish the facts of your citizenship. Birth in the US, or a US citizen parent, decides this, not the passport you travel on.
3. Take advice before you sign. The self-certification is the one document in this process that cannot be quietly corrected later.
4. Reply truthfully. If you are a US citizen without a Social Security number, say exactly that, and tell the bank you are applying for one.
5. Start the Social Security number application. It gates the tax returns and it is the slowest step.
6. Gather six years of account records. For each non-US account, find the highest balance in each calendar year.
7. Choose the catch-up route and file. For most people that is the Streamlined Foreign Offshore Procedures, described below.
8. Give the bank the number when it arrives. That ends the annual letters.

Which IRS route fits once the bank is answered?

There are two main routes, and the choice turns on whether you intend to stay a US citizen.

The Streamlined Foreign Offshore Procedures are for people keeping their citizenship. They ask for the most recent three years of returns, six years of FBARs and a Form 14653 certification that the failure was non-willful. Eligible filers are not subject to failure-to-file, failure-to-pay, accuracy-related, information return or FBAR penalties. The returns need a valid taxpayer number, which for a US citizen means a Social Security number. Our guide to the Streamlined Foreign Offshore Procedures goes through the paperwork.

The Relief Procedures for Certain Former Citizens are for people who have already relinquished citizenship after 18 March 2010, have no filing history as a US citizen or resident, have a net worth under $2,000,000, and have an aggregate tax liability of $25,000 or less across the year of expatriation and the five years before it. The IRS confirms that someone without a Social Security number can still make a submission under these procedures, which makes this the one route that does not wait on the number. Our post on the tax implications of renouncing US citizenship covers the decision itself.

What people get wrong about FATCA letters

• "If I ignore it, nothing gets reported." The opposite is closer to the truth. Without a valid self-certification the account is treated as reportable.
• "I have a British passport, so I can tick 'not a US person'." Holding another nationality does not remove US citizenship, and a US birthplace needs the three documents listed above to be set aside.
• "No Social Security number means the bank must close my account." Notice 2024-78 gives banks a way to keep reporting existing accounts without one until the end of 2027.
• "The letter means the IRS is investigating me." The letter comes from the bank's own records search. It says nothing about IRS activity.
• "Moving to a different bank will solve it." A new account needs a fresh self-certification, and the relief for missing numbers does not extend to new accounts.
• "Renouncing makes the earlier years disappear." Earlier obligations remain, and the bank will still want the Certificate of Loss of Nationality.

Where to get help

US/UK Cross Border Tax is US CPAs and UK tax advisers working as one team, with offices in London, Manchester, New York and San Francisco. For someone facing the accidental American citizenship tax problem, that means one team answering the bank, running the catch-up filings through our streamlined filing service and keeping the FBAR and FATCA reporting consistent with what the bank has sent.

If a FATCA letter is sitting on your table, contact us before you reply to it. The reply is short, but everything that follows is built on it.