A passport is a necessary document for American citizens who travel abroad. Not only is it proof of citizenship, but it is often the only acceptable form of identification for foreigners in many nations. Most countries require at least six months validity on a passport for entry. Booking a trip with an expiring or expired passport requires immediate renewal of the document.

Contact the embassy or consulate of the country you plan to visit and ask about its visa requirements for Americans. If you need a visa, ask how long it takes to receive it. Because visa applications require a passport, be sure that the time it takes to renew your passport plus the visa processing time can happen before your planned departure date. If not, you need to change your departure date to accommodate those times or you won’t be able to enter the foreign nation.

Visit a passport photo shop to have your picture taken. You need one passport photo with your application.

Renew your passport by mail if you do not need a visa and your departure date is two to three weeks beyond your mailing date. If you do need a visa, the departure date must be at least four weeks from the mailing date. In addition, your expired passport must be undamaged, issued when you were 16 or older, and issued within the past 15 years. It must also be under your current name unless you can legally document your name change. Otherwise, you need to renew in person by calling the National Passport Information Center (877-487-2778) to make an appointment.

Fill out Form DS-82, Application for a U.S. Passport by Mail. You can fill out this form online and then print it, or you can print the blank form and complete it by hand. Do not forget to sign and date the application.

Prepare a padded envelope with Form DS-82, the expired passport, the passport photo and any fees. If your current name differs from the expired passport, you also need a marriage certificate or court order documenting that difference.

Mark “EXPEDITE” on the package if you need your passport within two or three weeks of mailing. Do not forget the extra fees for such a service.

Send the entire package to the address listed on the application using a traceable delivery method such as USPS Priority Mail with signature confirmation.

Book your trip as usual through your website, by phone or through the travel agent. You generally do not have to provide the passport number and expiration until you depart. However, if your booking agency asks, tell it when you expect to receive your passport.

Give the passport information to your international carrier or booking agent as soon as you receive your new passport.