The U.S. Transportation Security Administration has quietly proposed a new rule that would require travelers without proper identification to pay a service charge.

If you don’t have a form of ID that complies with the federal standard, like your driver’s license or passport, the TSA says you can still fly. You will be notified of your non-compliance, the agency warns, and may have to undergo additional security screening.

The Transportation Security Administration has proposed a rule that would charge travelers who lack a Real ID an $18 fee at security checkpoints, according to a notice published Thursday in the Federal Register.

Travelers who attempt to fly without a Real ID or a passport could be subject to a new airport security screening program that carries an $18 fee. On Thursday, the TSA announced another option for travelers who have yet to get their Real ID or are flying without their passport: the modernized alternative identity-verification program.

Under the "technology-enabled" program, a traveler would be required to pay a non-refundable fee of $18 to request an alternative identity verification. Once approved, the identity verification would be valid for 10 days.

As of May, TSA now requires to have a REAL ID-compliant form of identification. This can include a REAL ID-compliant driver’s license, a learn’s permit, or a passport, as well as a number of alternatives.