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I have dual as well with one passport expired. I was going to just use the one, and then do a LOE that the other passport is expired. I have my birth certificate to prove the citizenship of the one with the expired passport if necessary.

Tks for your reply. I was wondering if the fact of having a passport, even an expired one, wouldn't be enough to prove citizenship since you could not have one if you were not a citizen.
 
Tks for your reply. I was wondering if the fact of having a passport, even an expired one, wouldn't be enough to prove citizenship since you could not have one if you were not a citizen.

Though it is possible to lose citizenship in some cases, and this could happen after the passport has expired.