You may apply to renew your U.S. passport at any time. If your passport has expired or is about to expire, we strongly recommend that you take action now to renew your passport. Apart from the inconvenience you may incur in having to apply for a passport at short notice in the event of an emergency, every American abroad should have valid proof of his or her citizenship at all times.
If your most recent passport is an emergency passport issued for one year or less at a U.S. Embassy or Consulate overseas, please follow this link for instructions.
U.S. Passport Renewal