According to the U.S. Department of State, a passport can be renewed if it is undamaged and can be submitted with a renewal application, was issued when you were 16 or older, was issued within the last 15 years, and was issued with your current name (unless you can provide an original or certified copy of legal documentation of your name change such as a marriage certificate).
Why is it worth the time -- not to mention the money -- to renew your passport? Here are five good reasons:
Unexpected foreign travel. You may not have any international travel plans on the books, but should the need to travel abroad arise suddenly, expedited passport renewal can be a major headache and may require additional fees.
May be used as proof of employment eligibility. When you get a new job, you will typically be asked to complete an Employment Eligibility Verification Form, known as an I-9 form. A passport will prove both identity and employment authorization for purposes of an I-9 form. Otherwise, separate documents will be required for both, such as a driver's license and a social security card, or a school ID and a birth certificate.
Same-sex married names. The federal government now recognizes same-sex marriage, allowing same-sex couples to obtain passports under under their married names with sufficient documentation of their legal marriage. For same-sex couples living in states that don't recognize same-sex marriage, having a valid passport can prevent states from refusing to issue driver's licenses under a spouse's married name.
Alternate form of ID. Although decidedly more unwieldy than a driver's license or state ID card, a passport can serve as a substitute ID if your other forms of ID are misplaced or stolen, allowing you to purchase alcohol, board a flight, or do anything that requires valid identification.
Access to U.S. Embassy. If you are a U.S. citizen living abroad, having a valid U.S. passport may come in handy if you encounter any legal trouble that requires the assistance of the U.S. embassy.
Learn more about passports, visas, and border entry rules at FindLaw's Learn About the Law section on Visas.