FBAR maximum account value unknown: when to check item 15a

What FinCEN says about item 15a

Form 114, Part II, item 15a: "Amount unknown. Check this box if the value of the account cannot be determined." (FinCEN Form 114 line-item instructions, v1.4, January 2017).

FinCEN's maximum value page says who the box is for: "Filers with fewer than 25 accounts who cannot determine whether the aggregate maximum values exceeded $10,000 complete the account section for each account and check the "amount unknown" box, item 15a."

Note the bar FinCEN sets for item 15 itself: "a reasonable approximation of the greatest value", not an exact figure. Item 15a is for the case where even an approximation is impossible, not for a value that is merely hard to find.

Before you check the box: three ways to find the value

1. A transaction export with a running balance. If your bank or Wise lets you export the year as a CSV file, the highest balance after any line is the peak; the balance you held on January 1 counts too. The maximum value finder reads the file in your browser and finds the peak and its date; step 1 of the how-to guide shows it by hand.
2. Periodic statements. IRS: "U.S. persons may rely on periodic account statements issued at least quarterly to determine the maximum value of the account if the statements fairly reflect the maximum account value during the calendar year." (Publication 5569, Rev. 3-2022). FinCEN says the same: statements "may be relied on if they fairly reflect the maximum account value". Take the highest closing balance across the statements, in the account's own currency.
3. A closed or inherited account. Ask the institution for the year's statements. The IRS expects you to keep them as well: For each account keep the name on the account, the account number, the name and address of the foreign bank, the type of account and the maximum value during the year, for five years from the due date of the FBAR.

Once you have a figure in the account's currency: Convert the maximum account value of each account into US dollars at the Treasury's rate for the last day of the calendar year. The December 31 rates are on the FBAR exchange rates page. If no Treasury rate is available, use another verifiable exchange rate and provide the source of that rate.

What you still fill in when the value is unknown

Item 15 stays empty, item 15a is checked, and items 16 to 23 are completed as for any other account. The account section of Form 114:

Does an unknown value still mean I have to file?

FinCEN's 15a sentence applies to people who cannot determine whether the aggregate exceeded $10,000: they complete the account sections and file. For many accounts the question answers itself. If one account alone ever held more than the amount below during 2025, the aggregate exceeded $10,000 and an FBAR is due; the threshold check adds several accounts.

So an account that held more than 8,510 EUR or 7,430 GBP at any point in 2025 already settles the filing question, even if its exact peak is unknown.

25 or more accounts: item 14, not item 15a

Form 114, Part I, item 14: "If the filer has a financial interest in over 25 or more foreign financial accounts check the yes box, and enter the total number of accounts in 14a. Leave blank Part II (Continuation of Separate Accounts) or Part III (Joint Accounts) of this report, but maintain records of the information." The records you keep for those accounts are the ones listed above (name on the account, number, institution, type, maximum value).

What the finder does when it cannot complete a value

The finder leaves item 15 blank and marks the account as still needing an exchange rate when the Treasury published no rate for its currency that year; you can type another verifiable rate with its source, as FinCEN allows. It does not decide item 15a for you: whether a value "cannot be determined" is your call, made on your statements. When to file is on the FBAR deadline page.