Can we file one FBAR if one spouse has an account in their own name?

FinCEN's condition applies to the non-filing spouse: every foreign account that spouse must report has to be jointly owned with the filing spouse. The filing spouse can have accounts of their own. A separately owned account below $10,000 is still reportable if its owner's foreign accounts together exceed the threshold.⁠^{[1]Source 1}⁠^{[2]Source 2}

A and B jointly own a foreign account worth $12,000. B also owns a $500 foreign account alone. B must report both, so A can't cover B under the spousal exception. If instead A owns that extra $500 account, A can report the joint account and their own account while B uses the exception. The FBAR must be timely and both spouses must have signed Form 114a.⁠^{[1]Source 1}⁠^{[3]Source 3}

List the joint and separate accounts for each spouse and decide which spouse would file. Check that the non-filing spouse has no other account or signature authority to report. Then confirm the timely-filing and Form 114a conditions.⁠^{[1]Source 1}⁠^{[3]Source 3}