In most cases, to enter the United States, you must have a passport that is valid for at least six months after the date you enter. However, the United States has an agreement with some countries (including Ireland) that allows you to enter on a current passport up to the actual date of expiration. An Irish/EU passport need remain valid only for the duration of the holder's stay in the United States. However, if you are traveling visa-free on the Visa Waiver Program (VWP) and your passport is valid for less than 90 days, you will generally be admitted only until the date the passport expires. Click here for List of Countries with Agreements with the United States to Extend Passport Validity.