If a salary jump eventually disqualifies a borrower for the capped monthly payments, they would still be responsible for the cost of the loan and the interest that accrued up to that point. Monthly payments still couldn't exceed what they would be under a standard 10-year repayment plan. Of course, borrowers could opt to pay off debts faster if they chose.

There are already some options for those who can't afford big monthly payments, such as long-term payment plans spanning up to 30 years. But eligibility requirements are stricter, and monthly payments can still be high.

The government also offers a program similar to IBR called the income-contingent repayment plan. That plan is not as lenient as the new one, however, with payments capped at 20 percent of income beyond 100 percent of the poverty level. And it's also only available for direct federal loans.

The new program will be available for direct federal loans, as well as federal loans administered through private lenders. Most of those enrolled in the income-contingent plan are expected to switch over to the new program.

Parent PLUS loans, the federal loans parents can take out to pay for their children's education, are not eligible for either payment plan.