More than 7 million student loan borrowers are in a defunct payment plan — what that means for their money

Read more CNBC personal finance coverage
"They may not need to make a payment today, but their loan debt is quietly growing, and they are not making progress towards any loan forgiveness provided under the law," said Scott Buchanan, executive director of the Student Loan Servicing Alliance, a trade group for federal student loan servicers.

"With 7.2 million borrowers filing an income-driven repayment plan request, the U.S.

Department of Education is unlikely to be able to process those forms in a timely manner," he said.

"Borrowers who file the form now will be at the front of the list."
As a result, they'll likely avoid long wait times and more interest accruing on their debt, Kantrowitz added.

Switching repayment plans can be costly, too
It's understandable that borrowers are worried about their payments jumping under other plans.

Still, very-low-income borrowers could have a monthly bill of just $13 under IBR, according to a calculation by Kantrowitz.

There are tools available online to help you determine how much your monthly bill would be under different repayment plans.

Borrowers worried they can't afford their monthly payments should also see if they are eligible for any payment pauses where interest won't accrue — such as the unemployment deferment if you have direct subsidized loans, consumer advocates say.

If your repayment plan application was denied, whatever the reason, you should submit a new one as soon as possible, experts say.

While there's a large backlog of repayment plan applications, the Education Department has recently made progress in processing the forms.