Bad news for Kentucky, Maine, Minnesota, Missouri, Montana, Oklahoma, Pennsylvania, South Carolina, and Washington: Starting January 22, 2018, driver's licenses issued by these states will no longer be accepted at TSA checkpoints. They fail to meet the federal government’s minimum security standards under the Real ID Act. Instead, travelers have to use another form of identification to pass through security for domestic flights—think military ID, permanent resident card, or passport.

While there's been some confusion about when Real ID Act will be enforced—and what, exactly, the Real ID Act is—the TSA has taken advantage of the busy holiday season to warn travelers that they can expect changes in 2018. It announced that it would start posting notices the week of December 12, and signs have already been spotted at Chicago O'Hare and Minneapolis-St. Paul International airports.

Courtesy Department of Homeland Security

In 2005, following the recommendation of the 9/11 Commission, the Real ID Act was passed by Congress with the end goal of making fake IDs harder to get. U.S. states and territories were supposed to enforce stricter requirements when issuing IDs—demanding more proof of identity, incorporating anti-counterfeit technology, and doing background checks for those issuing licenses. If the nine aforementioned states make a move to change their processes, the TSA has said it may grant extensions, and will update its signage appropriately.

Travelers who aren't from those nine states won't be affected by the enforcement of rules in 2018, but the government has mandated that all travelers have identification that complies with the Real ID Act by 2020. At present, only 24 states and Washington, D.C. have licenses that meet the standards set by the act. Remaining states have an extension through October 10, 2017 as they work to revamp their existing practices. Unsure about what will happen with your state? Monitor its status here, and play it safe by making sure your passport is up to date.