U.S. passports cannot be extended. If you are travelling abroad and your passport validity expires, you can apply for a full-validity regular passport or a limited-validity emergency passport. Replacing a full-validity passport requires a minimum of two weeks. An emergency passport can usually be issued within two business days.
Limited validity passports can be issued for a variety of reasons, but are usually issued for emergency travel back to the United States. Such passports, valid for a maximum of twelve months, can only be replaced with a full-validity passport. We cannot issue a second limited validity passport to replace an earlier one; you are expected to provide the information needed to enable us to issue a full validity passport following the issuance of a limited one.
Since there are various reasons for limiting a passport, a case by case examination must be made by the consular section of the Embassy before determining whether a passport can be extended. Often the passport can be extended only after authorization is received from the Department of State in Washington, D.C. Full-validity passports are printed only in the United States. Because of these potential delays, you should not make any unchangeable travel plans until you receive your new passport.
Contact the American Citizens Services unit for more information on applying for an emergency limited-validity passport.