Missed FBAR: Maximum Balances When UK Statements Are Gone

A Missed FBAR can still be prepared when UK statements have gone. FinCEN asks for a reasonable approximation of each account's greatest value, not a perfect figure. Rebuild the peak from surviving evidence, record how you reached it, and keep that file. No IRS-approved estimation formula has been published.

That last sentence is the one most pages on this subject avoid. Search for the problem and you will find two kinds of answer: a line telling you to use the highest balance you can find, or a suggestion that overestimating is fine because the form is informational. Neither helps a client whose savings account vanished in a bank merger, whose peak balance fell between two surviving year-end letters, and whose old passbook account has no number anyone can trace. This guide, written by the cross-border team at Jungle Tax, addresses that file: what the rules say, where they stop, and how to build a reconstruction that stands up if someone reads it.

We assume you have already established that the account is reportable and that the six-year FBAR window applies. Conversion uses the Treasury year-end rate, so the working below stays in sterling until the last step.

What do the regulations actually require on maximum value?

Less than people assume, and that helps. Three primary sources do the work.

• The standard. FinCEN's FBAR line-item instructions define maximum value as a reasonable approximation of the greatest value of currency or non-monetary assets in the account during the calendar year. IRS Publication 5569 uses the same concept.
• The statement safe harbour, and its limit. Periodic statements may be relied on if they fairly reflect the maximum. Publication 5569 frames this around statements issued at least quarterly. A statement is a permitted source, not a mandatory one, and a statement that misses a known spike does not fairly reflect the peak.
• The record. Under the recordkeeping rule at 31 CFR 1010.420, filers keep the account name, number or other designation, institution name and address, account type and maximum value. FinCEN's instructions run the five years from April 15 of the following year, or from the filing date if later. For a late filer, that later date is the one that matters: the reconstruction file becomes the record, and it starts its own five-year life on the day you file.

Here is what the rules do not say. They set no hierarchy of evidence, no uplift percentage, no tolerance band, no minimum number of data points and no prescribed wording for a method note. The FBAR has no field for explaining an estimate. We have found no IRS or FinCEN publication approving a specific estimation method for lost statements. Any firm that describes its approach as IRS-accepted should be asked for the citation. The framework below is our practice built around the standard, and should be read that way.

Why are UK statements gone in the first place, and can they still be recovered?

The reason matters, because it tells you whether a request is worth making. Banks hold customer records under regulation 40 of the Money Laundering Regulations 2017. The general period is five years from the end of the business relationship, with transaction records capped at ten years, and personal data must then be deleted unless an exception applies. Three consequences follow.

• An account still open is the easy case. The five years have not started, so transaction history from 2020 onwards should be within the cap. "Online banking only shows two years" describes a portal, not the archive. Ask for archived statements.
• An account closed in 2021 or earlier is at the edge. The five-year period may already have run. Some institutions keep records for longer under their own policies, but none has to. Send the request now, because this evidence shrinks every month you wait.
• A merged or transferred account has a successor. Where a book of savings accounts moved to another institution, records may have moved with it, sometimes into a legacy system that branch staff cannot see. Ask the successor specifically for the legacy brand's archive.

The formal lever is a data subject access request. The Information Commissioner's Office says organisations usually have one month to respond. It works for an American living in New York as well as one in London. A bank may treat a request for "statements" as a request for documents rather than personal data, so ask for transaction records, balance history, account opening and closure details, customer notes and any FATCA self-certification or reporting records. Name every sort code, brand and address you can.

Run HMRC's own access route in parallel. HMRC directs people to the personal tax account first, which covers the current year and the last five, and reserves a formal request for older data. It should reply within one month, or up to three for complex requests. For a catch-up filed in late 2026, the 2020/21 tax year may already sit outside the online view.

Evidence hierarchy: how we rank what survives

This table is our own ranking, not an official one. It runs from the evidence closest to the bank's ledger to the evidence furthest from it. Reach as high as you can for each account and each year, and record why you could not go higher.

Tier	Evidence	Where it comes from	What it proves	Weak point
1	Full statements or transaction export	Client files, archive request, access request	Actual running balances and the true peak	Quarterly statements can miss intra-period spikes
2	Bank-issued point values: year-end letters, closing statement, maturity letter, audit confirmation	Client files, the bank, mortgage or lending files	The exact balance on a stated date	Silent on every other date
3	Interest certificates and the bank's interest reports	Bank, HMRC tax calculation, personal tax account	Income, from which an average balance can be implied	An average is not a peak, and the rate must be known
4	Transfer trail on a surviving counterpart account	Statements of the other account, completion statements, sale paperwork, contract notes	Dated movements in and out	Shows direction and amount, not the balance they landed on
5	Tax filings: Self Assessment returns, HMRC calculations, earlier US returns with Schedule B	Client, HMRC, IRS transcripts	That the account existed; interest totals	Often aggregated across accounts and on a different year basis
6	Third-party snapshots: lender net worth forms, investment manager valuations, employment relocation paperwork	Client, lender, manager	A declared value near a date	Self-declared figures may be rounded or dated
7	Signed client recollection supported by context	Client memo	Last-resort narrative	Uncorroborated; never the sole basis if anything above can be obtained

What does a reasonable reconstruction look like?

The method we use is a roll-forward tested against interest. Each step answers a different question.

1. Anchor. Fix every known balance on a known date. These come from tier 1 and tier 2 evidence, and they are the only hard points you have.
2. Roll. Between anchors, apply each dated movement from the transfer trail. Inflows raise the balance and outflows lower it. The highest point on that line is your provisional peak.
3. Reconcile to interest. Model the interest that balance line should have earned at the account's rate. Compare it with the reported interest. A close match suggests the line is complete. A material shortfall in modelled interest suggests you have missed a deposit.
4. Adjust for what cannot be seen. Add accrued interest and identify known cash events such as a bonus, a property sale or a share vesting. State the assumption rather than burying it in a rounded figure.
5. Round up to a defensible number. FinCEN rounds reported figures up to the next dollar anyway. Rounding up at the reconstruction stage is sensible. Padding is not: an unexplained 20% cushion undermines every other figure in the file.

Two UK traps catch generalist preparers. First, HMRC and most UK interest documents run on the tax year, 6 April to 5 April, while the FBAR runs on the calendar year. A 2021/22 interest figure spans parts of two FBARs and must not be dropped into either as if it were aligned. Second, interest implies an average balance, and an average is structurally below the peak unless the balance never moved. Treating implied average balance as the maximum is the most common error we see in self-prepared reconstructions, and it fails the stated standard on its face.

Can the IRS's own estimating procedure guide you?

It can guide you, though it does not bind you. IRM 4.26.16.5.5.3 tells examiners what to do when they cannot obtain a violation-date balance after reasonable efforts. They may estimate from available information, including a balance on another date, and they document their efforts, the fact of estimation, the reason, and the information used, such as known transfers between dates. That passage instructs examiners on penalty computation. It gives filers no method and no protection. Even so, it is the clearest public signal of what the IRS itself regards as an orderly estimate, so we model the file on it.

Worked example: five accounts, one reconstructed year

The client is a US citizen and London-resident managing partner preparing FBARs for 2020 to 2025 under the Streamlined Foreign Offshore Procedure. All figures are invented for illustration. Calendar 2021 is the hard year, because a savings account (Account B) closed in May 2022 after a merger of its brand and the statements cannot be found.

Account B, surviving evidence:

• A balance letter issued for a mortgage application: £310,000 at 31 December 2020 (tier 2).
• Annual interest credited each 5 April, with the April 2021 credit estimated at £1,400 from the prior year's return.
• Account A's statements showing £150,000 sent to Account B on 14 June 2021 and £60,000 received from it on 2 November 2021 (tier 4).
• HMRC's 2021/22 tax calculation showing £1,840 of interest on Account B, with the published rate at 0.45% taken from a client rate letter (tier 3).

The balance line is:

Period in 2021	Movement	Balance
1 January	Anchor from letter	£310,000
5 April	Interest credit, estimated +£1,400	£311,400
14 June	Transfer in +£150,000	£461,400
2 November	Transfer out −£60,000	£401,400

Now the test. Weighted across the 2021/22 tax year (69 days at £311,400, 141 at £461,400, 154 at £401,400), the average is about £407,600. At 0.45% that models to about £1,834 of interest, against £1,840 reported. A £6 gap gives good comfort that no sizeable deposit is missing. Reported maximum: £462,000, rounded up.

Had the preparer simply divided the interest by the rate, the answer would be £408,889, which understates the peak by £53,111. That is the danger of treating the average as the peak.

The full 2021 position:

Account	Best evidence	Method	2021 maximum	31 Dec 2021
A: current account, open	Tier 1	Highest running balance on statements	£186,400	£94,000
B: savings, closed May 2022	Tiers 2, 3, 4	Roll-forward, reconciled to interest	£462,000	£401,400
C: 12-month fixed deposit, matured September 2021	Tier 2	Maturity letter, including final interest	£251,100	£0
D: investment account, transferred 2023	Tiers 2, 6	Highest known valuation plus stated market test	£1,163,000	£1,140,000
E: old passbook savings, number unknown	Tier 7, supported by a 2018 letter	Last known £2,300 plus rate allowance	£2,400	£2,400
Total			£2,064,900	£1,637,800

Account D deserves a comment. Surviving valuations show £1,140,000 at the year end and £1,128,000 at 30 September, and the £251,100 from Account C arrived in September. Between valuations, an invested portfolio moves. We compared a broad market index's 2021 high against its closing level, found the high about 2% above the close, and applied that to the whole portfolio: £1,162,800, rounded up to £1,163,000. This is a judgement, not a rule. An index is a rough proxy, and we would refine it if the asset mix were known. Writing it down lets a reader disagree with an assumption rather than doubt the entire figure.

The two totals differ for a reason. Each FBAR line carries its own peak, even though the peaks fell on different days. The year-end column matters separately: under the Streamlined Domestic Offshore Procedure, the 5% penalty base is built from year-end balances, not FBAR maximums. Our client is non-US resident, so no such penalty applies. Had they lived in the US, using the wrong column would produce a 5% charge of £103,245 instead of £81,890 for this year alone, and the highest year would still need to be identified across the covered period.

How the six-year file looks once complete

Account	2020	2021	2022	2023	2024	2025
A	Actual	Actual	Actual	Actual	Actual	Actual
B	Reconstructed	Reconstructed	Reconstructed, closing statement	Closed	Closed	Closed
C	Letter	Letter	Matured	Matured	Matured	Matured
D	Valuation plus test	Valuation plus test	Valuation plus test	Actual, new custodian	Actual	Actual
E	Estimate	Estimate	Estimate	Estimate	Estimate	Estimate

A grid of this kind gives a reviewer the file's strength at a glance, and shows that recent years rest on hard data. It also shows exactly where any later-found statement should be applied.

How do you record the estimate method in the file?

Because the FBAR has no method field, the file note is the only place the reasoning exists. We prepare one note per account per year. It should stand on its own, so that a reader five years from now does not need to phone anyone.

• Account identity: name on the account, institution then and now, designation used, type.
• Recovery efforts: each request, the date, the addressee, the response, and copies. Include refusals, because a letter confirming records were destroyed is valuable evidence.
• Statement that the figure is an estimate, and why estimation was necessary.
• Evidence relied on, by tier, with an index to the copies.
• The arithmetic, shown as a balance line, and the interest reconciliation.
• Assumptions and any judgement calls, including what you considered and rejected.
• Whether the figure feeds other filings, such as Form 8938, and that it was used consistently.
• Preparer, reviewer and date, plus the client's signed confirmation that the cash events listed are complete to the best of their knowledge.

The client confirmation is not a formality. Under the IRS streamlined procedures, submissions may be checked against information from banks and other sources, and the taxpayer certifies non-willful conduct. A careful reconstruction supports that account of events. A figure chosen for being low does the reverse. If the estimate is significant to the narrative, it can properly be mentioned in the non-willful statement, but we do not attach working papers unless asked. The Streamlined Domestic pages expect supporting foreign asset records to be kept and provided on request, and we prepare the same file for foreign-resident clients.

What should you do about an account whose number is unknown?

This is the question no competing page we reviewed answers properly. FinCEN's published guidance gives Item 18 the heading "Account number or other designation". The instructions then ask for the number the institution uses, and tell filers to provide as much information as possible. Separately, the instructions prohibit certain text entries, including UNKNOWN, NONE and XX. So advice circulating online to write "unknown" or to pad digits with XX runs directly against that list.

FinCEN's electronic filing requirements for batch filers (the published version we reviewed is dated 2015) mark the field as required and list a blank account number as a file error that must be corrected. We have found no published instruction for an account number that is truly unrecoverable. In that gap, we work through the following order.

What you have	What we do	Status
Full number on any document, cheque, passbook, or old direct debit form	Enter it, stripped of spaces and punctuation as the instructions require	Compliant
Sort code plus roll number or a building society reference	Use the identifier the institution actually used to designate the account	Within "other designation"; note in file
IBAN or a customer or portfolio reference	Use it, recording its relationship to the account	Reasonable reading of "other designation"; note in file
Partial number only	Press the bank first through an access request; if refused, enter what is held without a filler code and record the gap	Rules silent; judgement call
Nothing, bank confirms the account but cannot supply a number	Obtain the bank's written reply and use any reference it quotes for the account, then record that this is the sole designation available	Rules silent; document thoroughly
Nothing, bank has no trace and no paper exists	Stop and assess whether the account's existence in the window can be shown at all, then settle how to report it with a specialist preparer before filing	Rules silent

Before you reach the bottom rows, look in the places clients forget: payslips from the first UK employer, mortgage direct debit forms, old tax certificates, lender affordability packs, Self Assessment working papers and, on the HMRC side, the interest data banks report after each 5 April. HMRC's tax calculation usually shows interest by account, and it often reveals an account the client had forgotten. For an old dormant balance, the institution's dormant-account team can often confirm the position when branch staff cannot.

On Item 17, the instructions ask for the institution in which the account is held but do not address mergers. Our practice is to report the name that held the account during that calendar year and note the successor in the file, adjusting where the legacy brand was only a trading name. Where the correct name is a live question, that too belongs in the note.

When should you tick "amount unknown"?

Rarely. Item 15a lets a filer tick the box if value cannot be determined, and the general instructions apply it to filers with fewer than 25 accounts who cannot determine whether the aggregate exceeded $10,000. It is available, but it is the last rung. For a client with a well-supported seven-figure total, an old passbook account with a dated letter is not undeterminable. A figure with a stated basis is more informative than a tick, and the box does not relieve anyone of the recordkeeping rule. Reserve it for an account with no anchor of any kind, and explain the search in the file.

How does this interact with the UK side?

Here is where US-only guides stop, and where the most uncomfortable findings often appear. The reconstruction may show that the interest on Account B was never in the Self Assessment return, or that an investment account produced unreported gains. A US file built to be thorough can therefore document a UK shortfall.

Issue	US (IRS and FinCEN)	UK (HMRC)
Purpose of the figure	Account peak for FBAR, plus maximum and year-end values for Form 8938	Income and gains actually arising; balances matter only as evidence
Period	Calendar year	6 April to 5 April
Standard for estimates	Reasonable approximation of greatest value; no prescribed method	Best information available; returns have a mechanism for provisional figures, to be finalised where possible
Look-back in a catch-up	Six FBAR years and three return years under streamlined filing	Depends on behaviour; up to 12 years for offshore matters and 20 for deliberate conduct
Route	Delinquent FBARs marked as streamlined with returns and certification	Ordinary amendment if in time, or a disclosure through HMRC's digital service where appropriate
Third-party data	FATCA reporting of US-owner accounts via HMRC	Bank interest reports; automatic exchange on overseas accounts

The FATCA line deserves a moment. Since the UK agreement took effect, UK institutions have reported identified US-owner accounts to HMRC for onward exchange to the IRS, including year-end balances. So the IRS may hold a bank-reported figure for an account you are now estimating. If your year-end reconstruction sits well below it, the file has a problem you cannot see. That is why we ask the bank for its FATCA reporting records in the access request, and why we reconcile year-end positions as well as peaks.

Form 8938 is the other cross-check. It applies only in the covered return years and uses its own thresholds, but it asks for maximum value and, for many taxpayers, year-end value too. A peak on the 2024 FBAR that differs from the same account on the 2024 Form 8938 needs an explanation in the file. Our UK tax team and US preparers work from one set of figures for that reason.

What happens if statements turn up after filing?

You correct it. FinCEN's instructions provide for an amended report, with the Amend box checked and the prior BSA identifier quoted. A filed estimate is not a permanent position. A material difference justifies an amendment and a short addition to the file note, and small differences within what the reconstruction anticipated should still be recorded. Late-arriving evidence is a further reason to start the requests early and date them, since it shows that the estimate was made in good faith at the time.

Timing does not need to wait for every answer. Given a one-month response period that can stretch, a sensible sequence is to send all requests in week one, build the balance lines from what is in hand, then finalise at around week eight. Late filers should weigh this against their own position, including exposure discussed in our FBAR penalty calculator. The IRS's foreign-resident instructions call for the late-filing reason to be entered as "Streamlined Filing Compliance Procedures" under "Other", and that annotation applies regardless of how the balances were established.

Common failures in reconstructed files

• Using an implied average as the maximum.
• Dropping tax-year interest into a calendar-year calculation without splitting it.
• Reporting the year-end value for an account that peaked mid-year, particularly in the year of a bonus or a property sale.
• Applying the same unexplained round-up to every account, which reads as a guess.
• Letting the FBAR, Form 8938 and UK figures diverge because three people prepared them.
• Keeping no copies of refusal letters, so the efforts made cannot later be shown.
• Treating a portal's date limit as the bank's retention limit, and estimating when an archived statement was available for the asking.

Our clients typically arrive with several institutions, some gone by name, across more than one country. That is routine work for our high-net-worth team, and a well-kept file usually proves stronger than clients expect once the surviving evidence is laid out in order.

Speak to us in confidence

If you have UK accounts in the six-year window and the paperwork has thinned out, we can tell you quickly how much can be recovered and what a defensible file would look like for your accounts. Please contact our cross-border team for a confidential consultation, ideally before any bank request is sent, so that the requests are worded once and worded correctly.