A UE ID, or Universal Enrollment ID, is a number assigned to an individual when they apply for TSA PreCheck online and before their interview. It is also sometimes referred to as a Unique Entity Identification (UEID) number, which is issued by the government and required for companies doing business with the government or receiving grants. The UE ID is not the same as the Known Traveler Number (KTN), which is a unique number assigned to individuals who have been approved for TSA PreCheck. However, you can use your UE ID and date of birth to conduct a KTN lookup. The UE ID is included on the receipt you receive when you are fingerprinted for TSA PreCheck enrollment. It is important to keep this receipt as you will need it to look up your KTN online.