As of March 2015, TSA charges $85.00 for participation in its pre-check program. Participants must be part of the U.S. Customs and Border Protection Trusted Traveler program, including Global Entry, NEXUS, SENTRI or they must have a Known Traveler Number.
Applicants for the Known Traveler number may apply online. An appointment is made at a TSA Pre-Check application center, where the applicant pays the fee, gets fingerprinted and provides valid government identification. If approved the applicant is sent the Known Traveler Number by regular mail or online. The number is used when making airline reservations online or with a travel agent and triggers the pre-check.