WASHINGTON, D.C.: Air travelers in the United States who show up at airport security without a REAL ID will be charged a US$45 fee starting in February, the Transportation Security Administration (TSA) said this week.

Although the updated identification standard has been required since May, passengers without it have so far been allowed through security after extra screening and a warning. The Department of Homeland Security says 94 percent of travelers already meet the requirement and that the new fee is meant to push remaining passengers to obtain the compliant ID.

REAL ID is a federally approved driver's license or identification card created after the September 11, 2001, attacks, requiring additional documentation at motor vehicle agencies. The rollout, initially slated for 2008, has faced years of delays.

Beginning February 1, domestic flyers 18 and older who do not have a REAL ID or another acceptable credential, such as a passport, will need to pay the non-refundable charge to verify their identity through TSA's alternative "Confirm.ID" system.

TSA officials cautioned that paying the fee does not guarantee successful verification. Travelers whose identities cannot be confirmed may still be denied entry to the security checkpoint. Approved verifications, however, will be valid for a 10-day travel period.

The fee can be paid online before arriving at the airport, or at the airport prior to entering the security line, though TSA said the process may take up to 30 minutes. The agency initially proposed an $18 fee but increased it after determining program costs would be higher than expected.

Other acceptable IDs include military credentials, permanent resident cards, and photo IDs issued by federally recognized tribal nations. TSA also accepts digital identification via Apple Wallet, Google Wallet, and Samsung Wallet at more than 250 U.S. airports.