You must have a valid passport to enter the UK. It should be valid for the whole of your stay. You may also need a visa, depending on which country you're from. Check if you need a visa to come to the UK.

Yes, you absolutely need a valid passport to travel to England from outside the Common Travel Area (which includes the UK and Ireland). For U.S. citizens, the passport must be valid for the entire duration of your stay. As of February 25, 2026, there is a critical new requirement: all visa-exempt travelers, including those from the U.S., Canada, and Australia, must obtain an Electronic Travel Authorisation (ETA) before flying. This digital permission costs £16 (approx. $20) and is linked to your passport. Without an approved ETA, you may be denied boarding by your airline. While Americans generally do not need a formal visa for stays under six months, the combination of a valid physical passport and an approved ETA is now the mandatory standard for entry into the United Kingdom.