Both lengths are valid
A BIC can be 8 or 11 characters (SWIFT, ACER). The 8-character form names the bank, country and location. The 11-character form adds a branch identifier. A code of 9 or 10 characters is always a mistake: a branch code is exactly three characters, so the checker tells you how many are missing or extra.
What an 8-character code means
The EU Agency for the Cooperation of Energy Regulators (ACER), in a reporting guidance answer, says that where an 8-character code is given "it may be assumed that it refers to the primary office", and that XXX is the branch code for the primary office. In its own reporting it asks for XXX to be added, with the example 12345678XXX (ACER).
That answer is about ACER's reporting rules. Banks and payment forms may have their own. The safe reading:
| You have | The form asks for | What to do |
|---|---|---|
| 8 characters | 8 or 11 | Give the 8 characters |
| 8 characters | Exactly 11 | Adding XXX is the usual form; if the bank's instructions say something else, follow them |
| 11 characters ending in XXX | 8 | The first 8 refer to the same primary office |
| 11 characters with another branch code | 8 | Do not cut it. Ask the bank which code to use; the branch may route the payment |
Codes the banks publish, in both lengths
Read on each bank's own page on October 30, 2026:
| Bank | Code as published | Length | Note |
|---|---|---|---|
| Chase | CHASUS33 | 8 | Chase |
| Wells Fargo | WFBIUS6S | 8 | Wells Fargo |
| Navy Federal | NFCUUS33XXX | 11 | Branch XXX, so NFCUUS33 is the same primary office (Navy Federal) |
| USAA (intermediary) | IRVTUS3NXXX | 11 | The Bank of New York's code, given by USAA for incoming international wires (USAA, PDF) |
| U.S. Bank | USBKUS44IMT | 11 | Branch IMT: give all 11 characters (U.S. Bank) |
U.S. Bank is the case where length matters. Its page gives USBKUS44IMT, not USBKUS44. Dropping IMT would point the payment at a different identifier from the one the bank asks for.
The checker's note
When you enter 8 characters, the checker shows the same code with XXX added as a hint, and the "before you send" list repeats it. It does not mean that every bank or form accepts it. When you enter 11 characters with a branch other than XXX, it tells you to pass on all 11.
What the policy says about use on the network
For network use, each user must have at least one valid connected 8-character BIC (SWIFT). Branch codes hang off that 8-character base. See BIC position 8 for connected and non-connected codes.
Left out on purpose
We do not say which length a particular app or payment form requires. Follow the instructions you were given, and check the result in the BIC checker.