As of September, active service members who tap the military’s tuition assistance program could be financially on the hook if they get bad grades.

Active members of the military can get up to $4,500 a year in tuition assistance. Under the current rules, they just have to pass classes they take off-duty to get tuition covered up to 100 percent, depending on the branch of the military they’re in.

But starting in early September, troops will have to earn a C or better in undergraduate classes, and a B or better in graduate work. And they can’t settle for grades of “incomplete.” Otherwise, they’ll have to pay back the course tuition back.

“Tuition dollars and military student time is both limited and valuable,” says Defense Department spokesman Lt. Cmdr. Nate Christensen. “So, we want to make sure they maintain focus and have an understanding of the expectations that are required of them.”

Christensen says the Pentagon could waive the requirements in certain cases and cut soldiers slack for events like deployments.

Emma Scherer of Student Veterans of America says the threat of paying back tuition for anything less than an average grade could scare people off.

“We don’t want to put roadblocks in the way of service members or veterans getting to education, and this clearly does that,” she says.

Student financial aid expert Mark Kantrowitz, publisher of Edvisors.com, says having to back-pay tuition could also disrupt service members’ long-term education plans.

“They’d either owe the military or owe the college, and that could have consequences for their ability to complete college,” he says.

The changes come as the Pentagon faces long-term budget cuts.