Air travelers in the U.S. without a REAL ID will be charged a $45 fee beginning in February, the Transportation Security Administration announced Monday.

The updated ID has been required since May, but passengers without it have so far been allowed to clear security with additional screening and a warning. The Department of Homeland Security says 94% of passengers are already compliant and that the new fee is intended to encourage travelers to obtain the ID.

REAL ID is a federally compliant state-issued license or identification card that meets enhanced requirements mandated in the aftermath of the Sept. 11, 2001, terrorist attacks.