Does the $10,000 FBAR threshold apply to each account separately or to all accounts combined?

Combined. The FBAR threshold is an aggregate test: you add the maximum value of every reportable foreign financial account and compare the total with 10,000 US dollars. Four UK accounts holding roughly 3,000 dollars each are individually below the threshold and collectively above it. Once the aggregate is exceeded at any point in the calendar year, every qualifying account must be reported on FinCEN Form 114, including small and dormant ones.

Do I have to report a UK cash ISA or stocks and shares ISA on the FBAR?

Yes. An ISA is an account held at a financial institution located outside the United States, so it is a foreign financial account for FBAR purposes. The ISA wrapper is a UK tax relief only, described by the government at gov.uk/individual-savings-accounts, and it carries no weight in US reporting. Report the ISA separately, using the highest value it reached during the calendar year converted into US dollars.

Do I report the year-end balance or the highest balance during the year?

The highest balance. FinCEN requires the maximum value of the account, being the largest amount appearing on any quarterly or more frequent statement issued during the calendar year. The 31 December balance is irrelevant except as one candidate for that peak. An account that held a large sum in March and was emptied and closed in August is still reported at its March peak, and still appears on the form for that year.

Which exchange rate do I use to convert pounds into dollars for FinCEN Form 114?

The Treasury's published rate for the last day of the calendar year being reported, applied to every account regardless of when its peak occurred. You do not use the rate on the day of the peak, the IRS yearly average rate used for income on Form 1040, or your bank's rate. If no Treasury rate exists for a currency, the instructions permit another verifiable rate provided you record its source, and all amounts are rounded up to whole dollars.

If I am over the FBAR threshold, do I automatically have to file Form 8938 as well?

No. They are separate reports with separate thresholds. Form 8938 for a taxpayer living abroad applies at more than 200,000 dollars on the last day of the tax year or more than 300,000 dollars at any time if unmarried, and 400,000 or 600,000 dollars if married filing jointly. Form 8938 is filed with your tax return; the FBAR goes to FinCEN. Test both separately, because you can be over one and under the other.

What should I do about FBARs I never filed for earlier years?

If your US returns are otherwise correct and only the FBARs were missed, the IRS position is to e-file the late reports as soon as possible through FinCEN's BSA E-Filing System, selecting a reason for late filing on the form. If your returns are also delinquent or inaccurate and the failure was non-willful, the Streamlined Filing Compliance Procedures provide the structured route, requiring three years of returns, six years of FBARs and a signed non-willfulness certification.

The $10,000 FBAR Threshold for Dual US/UK Nationals

The FBAR threshold is a single aggregate test: a US person must file FinCEN Form 114 if the combined maximum value of all foreign financial accounts exceeded 10,000 US dollars at any time during the calendar year. It is not a per-account test. It is not a year-end test. It has nothing to do with how much income those accounts produced, or whether any US tax is due. The IRS states the rule at https://www.irs.gov/businesses/small-businesses-self-employed/report-of-foreign-bank-and-financial-accounts-fbar and FinCEN administers the report itself at https://www.fincen.gov/report-foreign-bank-and-financial-accounts.

For a dual US/UK national holding real sterling balances, the practical consequence is blunt. You are almost certainly over the line, and the only questions worth your time are which accounts belong on the form, what number goes in each maximum value box, and how that filing sequences against the separate Form 8938 you may or may not also owe. In the returns we prepare, the FBAR is rarely the hard part of a cross-border engagement. It is, however, the part most often filed wrongly, because the person filing it reached for the December statement instead of the year's peak.

What is the FBAR threshold and why is it an aggregate test?

The FBAR threshold is 10,000 US dollars measured across every reportable foreign financial account you hold, added together, at the single highest point the combined total reached during the calendar year. The IRS wording is that a US person must file if the aggregate value of those foreign financial accounts exceeded 10,000 dollars at any time during the calendar year reported.

Three mechanical consequences follow, and each of them catches people out.

You add the accounts together. Four UK accounts holding the equivalent of 3,000 dollars each are individually far below the threshold and collectively above it. All four then go on the form.
Once you are over, you report everything qualifying. You do not report only the account that tipped you over, and you do not omit an account because it held 40 pounds all year. A dormant building society passbook account with a trivial balance still gets its own line.
The measure is a peak, not a position. A balance that existed for one afternoon counts exactly as much as a balance that sat there for twelve months.

There is a fourth point that dual nationals routinely misread. Being fully compliant with HMRC does nothing at all to reduce this. The United States taxes and reports on the basis of citizenship, so your British passport, your UK residence and your perfectly filed Self Assessment return are irrelevant to whether FinCEN Form 114 is due. Meanwhile the information is already moving in the other direction: under the UK-US Agreement to Improve International Tax Compliance and to Implement FATCA, signed on 12 September 2012, UK regulations impose obligations on UK financial institutions to identify, capture and report information to HMRC on financial accounts held by US citizens and entities, and HMRC exchanges that with the IRS. HMRC sets this out at https://www.gov.uk/hmrc-internal-manuals/international-exchange-of-information/ieim400040. Your UK bank has, in all likelihood, already told the IRS the account exists.

What counts as a foreign financial account for a UK resident?

A foreign financial account is an account at a financial institution located outside the United States. The test is geographic, not corporate. The IRS Internal Revenue Manual at https://www.irs.gov/irm/part4/irm_04-026-016 is explicit that the location of the account, not the nationality of the institution, determines its status, so accounts of US financial institutions located outside the United States are foreign accounts. A dollar account you hold at the London branch of a US bank is a foreign account. A sterling account at the New York branch of a UK bank is not.

For a UK-resident dual national, the reportable population usually looks like this.

UK current accounts and instant-access savings accounts, including accounts you regard as dormant.
Building society accounts and fixed-term deposit or notice accounts.
Cash ISAs and stocks and shares ISAs. The ISA wrapper is a UK tax relief, described by the government at https://www.gov.uk/individual-savings-accounts, where the maximum that can be saved across ISAs in the 2026 to 2027 tax year is 20,000 pounds. That relief is a UK concept only. To FinCEN an ISA is simply an account at a UK financial institution.
UK brokerage and investment platform accounts, including the uninvested cash sitting inside them.
Foreign mutual fund holdings, which for a UK investor typically means the UK-domiciled or offshore funds held on a platform.
Joint accounts, including accounts held jointly with a non-US spouse. The account is reported at its full maximum value, not at your share of it.
Accounts you do not own but can operate, where you hold signature or other authority.
Certain UK pension arrangements, which need looking at individually rather than assuming either way.

Some accounts are outside the net. The IRS lists exempted categories including correspondent and nostro accounts, government-owned accounts, accounts of international financial institutions, military banking facility accounts, and IRAs and tax-qualified US retirement plans where you are a participant or beneficiary. Direct ownership of UK real property is not an account and is not reported on the FBAR, although the bank account the rent flows into certainly is.

How do you determine each account's maximum value during the year?

You report the highest value the account reached during the calendar year, not the balance on 31 December. FinCEN's guidance at https://www.fincen.gov/reporting-maximum-account-value is that the maximum value of an account is the largest amount of currency and non-monetary assets appearing on any quarterly or more frequent account statement issued during the year. In practice, because UK banks issue monthly statements and most people have online access to daily balances, that means working from the finest-grained record you actually hold.

The failure mode we see most often is someone downloading twelve December closing balances and adding them up. That produces a number that is too low almost every time, and in the transitory-event cases below it can produce a number that is not merely low but wrong by an order of magnitude. If the account was emptied and closed in August, the August peak is still what goes on the form, and the account is still reported.

Two smaller mechanics matter. First, an account opened or closed mid-year is reported on the basis of its peak while it existed. Second, amounts are recorded in whole US dollars, rounded up to the next whole dollar, so a converted maximum of 15,265.25 dollars is entered as 15,266.

Which exchange rate converts sterling into dollars for the FBAR?

One rate, applied to every account. The FinCEN Form 114 instructions require non-US currency to be converted into US dollars using the Treasury's published rate for the last day of the calendar year being reported, and if no Treasury rate is available for a currency you may use another verifiable exchange rate provided you record its source. The IRS comparison page at https://www.irs.gov/businesses/comparison-of-form-8938-and-fbar-requirements states the same rule in shorthand: convert to US dollars using the end of the calendar year exchange rate.

Read that carefully, because it produces a result people find counter-intuitive. The peak is measured on the day it happened. The conversion is done at the 31 December rate. If a sterling account peaked in March and sterling then moved substantially by December, you still convert the March peak at the December rate. You do not use the rate on the day of the peak, you do not use the IRS yearly average rate that you used for income on Form 1040, and you do not use the rate your bank showed you. Where a client holds sterling, euro and dollar accounts, each account is valued in its own currency, each is converted at the same year-end date, and only then are the dollar figures added together to test the FBAR threshold.

Why one day can make an entire year reportable

This is where high-net-worth dual nationals differ from the general expat population, and it is the part the competing guides skip. A great many wealthy dual nationals deliberately hold thin UK cash balances. The money lives in US brokerage accounts, in a company, or in property. Their day-to-day sterling float genuinely sits below the FBAR threshold for eleven and a half months of the year. And then something completes.

A UK property sale settles. A shareholding is sold and the proceeds land as a cash balance in a UK brokerage account before being reinvested. A bonus or a carried interest distribution is paid into a UK current account and swept out to the United States three days later. A refinancing draws down and sits somewhere while a purchase is arranged. In each case the aggregate crosses 10,000 dollars for a matter of days or hours, and that is sufficient. There is no de minimis period, no averaging, and no relief for money that was only passing through. The year becomes a reporting year, and every qualifying account you held at any point in that year goes on the form, including the ones that never held more than a few hundred pounds.

Worked illustration, with figures used purely as an illustration. Assume a dual US/UK national resident in London. Across the year her UK current account peaked at 6,400 pounds, her instant-access savings account at 2,000 pounds, and the cash balance in her stocks and shares ISA at 800 pounds. Separately, the proceeds of a flat sale, 480,000 pounds, sat in her own UK current account for four days in September before being wired to a US brokerage account. Her current account peak is therefore not 6,400 pounds but approximately 486,400 pounds. Assuming, purely for illustration, a year-end conversion of 0.80 pounds to the dollar, the aggregate reportable maximum is in the region of 611,500 dollars rather than the roughly 11,500 dollars the ordinary balances alone would have produced. The actual figures must be converted at the published Treasury rate for 31 December of the year in question.

There is a nuance on the conveyancer's client account that deserves an honest answer rather than a confident one. Where completion monies sit in a solicitor's client account, the question is whether you are the owner of record or holder of legal title of that account, which ordinarily you are not, and whether any indirect financial interest arises. That analysis is fact-specific and worth doing properly. What is not in doubt is the leg after it: the moment the net proceeds hit an account in your own name at a UK bank, even for a single day, you have a foreign financial account with a very large maximum value, and the whole calendar year is reportable.

Do you have to report accounts you do not own?

Yes, if you hold signature or other authority over them. The Internal Revenue Manual defines this as the ability to control the disposition of money, funds or other assets by direct communication, whether in writing or otherwise, with the institution maintaining the account. Two useful limits are drawn in the same guidance: supervisory approval of disbursements does not by itself constitute signature authority, and authority limited to buying or selling investments without the ability to move funds out does not either.

For our client base this bites in obvious places. A business owner who is a signatory on the company's UK bank account. A director or officer named on a subsidiary's account. An investment banker who is a signatory on a fund's or a partnership's UK operating account. A person named on an elderly parent's UK account for practical reasons. None of these are your money, and all of them can be reportable. Note also that FinCEN has historically granted filing extensions to certain individuals whose only obligation is signature authority, so the position for those accounts should be checked for the specific year rather than assumed.

How does the FBAR threshold sequence against Form 8938?

These are two separate reports with two separate thresholds, two separate destinations and two separate deadlines. Crossing the FBAR threshold does not trigger Form 8938, and clearing the Form 8938 thresholds does not excuse the FBAR. The IRS sets the Form 8938 thresholds out at https://www.irs.gov/businesses/corporations/do-i-need-to-file-form-8938-statement-of-specified-foreign-financial-assets and each has two limbs.

Living abroad, unmarried or married filing separately: more than 200,000 dollars on the last day of the tax year, or more than 300,000 dollars at any time during the year.
Living abroad, married filing jointly: more than 400,000 dollars on the last day, or more than 600,000 dollars at any time.
Living in the United States, unmarried or married filing separately: more than 50,000 dollars on the last day, or more than 75,000 dollars at any time.
Living in the United States, married filing jointly: more than 100,000 dollars on the last day, or more than 150,000 dollars at any time.
Form 8938 is filed with your income tax return and is due on the date of that return including extensions. The FBAR goes to FinCEN, is due 15 April and carries an automatic six-month extension to 15 October.
The FBAR reports accounts. Form 8938 reports specified foreign financial assets, a wider category that can include holdings not held in an account at all.

The sequencing point that matters, and which almost nobody spells out: the two-limb structure of the Form 8938 test means a transitory peak is treated very differently by the two regimes. The one-day sale proceeds in the illustration above make the FBAR unavoidable and, on the any-time limb, will usually pull Form 8938 in as well for a filer abroad, even though the last-day balance was modest. The reverse also happens. A dual national with a settled 250,000 dollar equivalent sitting in a UK deposit account all year is over the FBAR threshold twenty-five times over but, if unmarried and living abroad, sits above the 200,000 dollar last-day limb and so is in Form 8938 territory too, while a married couple filing jointly on the same facts would not be. Run both tests. Never infer one from the other. The IRS side-by-side comparison at https://www.irs.gov/businesses/comparison-of-form-8938-and-fbar-requirements is the right starting point, and the identical values should appear on both forms wherever the same account is being reported.

When is the FBAR due and how is it filed?

The FBAR is an annual report due 15 April following the calendar year reported, with an automatic extension to 15 October if you do not meet the April date. You do not request that extension and there is no form to file for it. The report is filed electronically through FinCEN's BSA E-Filing System at https://bsaefiling.fincen.gov and it is not filed with your federal tax return, as the IRS confirms at https://www.irs.gov/newsroom/details-on-reporting-foreign-bank-and-financial-accounts. Filing your Form 1040 does not file your FBAR, and an extension of time to file your 1040 has no bearing on it.

Records are part of the obligation, not an optional extra. You are generally required to keep records for five years from the FBAR due date showing the name on each account, the account number, the name and address of the financial institution, the type of account and its maximum value. For UK accounts this is a practical warning as much as a technical one, because several UK banks purge online statement history after a limited period. Pull and store the statements while you can.

What if you crossed the FBAR threshold in earlier years and never filed?

This is the most common reason a dual national contacts us, and the answer depends on whether your US tax returns are otherwise in order.

Where the returns are filed and correct and only the FBARs were missed, the IRS guidance is to electronically file the late FBAR as soon as possible, and the BSA E-Filing System permits past years to be submitted. The form itself asks you to select a reason for filing late, so the explanation is captured on the report. Do not rely on any older commentary describing a separately named IRS delinquent FBAR page as a live route; that published page was withdrawn, and the current mechanism is the FinCEN e-filing route itself.

Where the returns are also late or wrong, and the failure was non-willful, the Streamlined Filing Compliance Procedures are the structured route. For a taxpayer meeting the non-residency test, the Streamlined Foreign Offshore Procedures require delinquent or amended returns for the most recent three years and delinquent FBARs for the most recent six years, together with a Form 14653 certification of non-willfulness, and eligible participants are not subject to failure-to-file, failure-to-pay, accuracy-related, information return or FBAR penalties. The IRS sets the terms out at https://www.irs.gov/individuals/international-taxpayers/us-taxpayers-residing-outside-the-united-states and defines non-willful conduct at https://www.irs.gov/individuals/international-taxpayers/streamlined-filing-compliance-procedures as conduct due to negligence, inadvertence, or mistake, or conduct that is the result of a good faith misunderstanding of the requirements of the law.

On exposure, deal in the framework rather than in headline numbers. The statutory non-willful penalty is up to 10,000 dollars per violation, adjusted annually for inflation, with the current adjusted amounts published in the Code of Federal Regulations rather than on the form; willful penalties are the greater of 100,000 dollars as adjusted or 50 percent of the account balance at the time of the violation. Importantly, following the Supreme Court's decision in Bittner, a non-willful penalty applies on a per-report basis rather than per account, so a single non-willful reporting violation results in a single penalty rather than one for each unreported account. The IRM discussion is at https://www.irs.gov/irm/part4/irm_04-026-016.

A working checklist before you file

List every account at an institution located outside the United States, including dormant, closed-during-the-year and joint accounts.
Add the accounts where you hold signature or other authority but no ownership.
For each account, find the highest balance shown on any statement during the calendar year, not the December balance.
Look specifically for one-off events: property completions, share sales, distributions, refinancings, insurance settlements.
Convert every account's peak into dollars at the Treasury rate for 31 December of the reported year, and round up to whole dollars.
Add the converted figures and compare with 10,000 dollars to confirm the filing requirement.
Separately run both limbs of the Form 8938 thresholds for your filing status and residence.
Retain the supporting statements for five years from the due date.

The FBAR threshold is deliberately low, and for anyone with real sterling wealth it functions less as a test than as an annual certainty. The work is not deciding whether to file. It is capturing the year's peaks accurately, catching the transitory events that never show up on a December statement, and making sure the numbers reconcile to whatever appears on Form 8938. That is compliance preparation, and it is what we do on every US/UK engagement we take on.