Question: Which Countries Require a US Passport Valid for at Least Three Months?
Many countries, including those European nations that participate in the Schengen agreement, require US passport holders to present passports valid for at least three months beyond their date of entry.
If you plan to visit any of the countries listed below, check your passport and make sure it is valid for at least three months past your projected date of arrival. If you need to renew your passport before you travel, allow at least two months for this process.
Countries Requiring Visitors to Hold a Passport Valid for at Least Three Months Past Entry Date:
Denmark (including the Faroe Islands and Greenland)
Vatican City (Holy See)
Source: US Department of State, Bureau of Consular Affairs. Country Specific Information. Accessed July 9, 2011.