The Consumer Financial Protection Bureau (CFPB) has found that student loan lenders have a reasonable incentive to make quickly paying off higher-interest loans more difficult for the buyer.

According to the Huffington Post, CFPB assistant director Rohit Chopra wrote a letter adding more criticism to the companies that collect federal student loans for the government. Much of CFPB's criticism has also been aimed at the government for not keeping enough of a watchful eye on its contractors.

Chopra said in a statement to borrowers posted on the CFPB's website that lenders may make paying off loans with higher rates "harder to navigate." Chopra posted a sample letter that borrowers can send to their lender asking for any excess money in a payment to be applied to the loan with the highest interest rate. He also indicated this method is an effective way to pay off higher-interest rate loans.

"Consider a borrower with $30,000 in private student loans spread over multiple loans at multiple rates," Chopra wrote in his letter. "These loans are part of a securitized pool and managed by a single servicer. If the borrower is looking to pay off these loans more quickly, the outcomes for the trust and its bondholders, the servicer, and the borrower vary based on how extra payments are processed."

Many college students need to take out multiple loans, most commonly one for every academic year attending school.

"While these differences may be small, servicers may not have the financial incentive to allow borrowers to target prepayments to a specific loan," Chopra wrote. "Ironically, creating obstacles for borrowers to direct payments to a specific loan can increase future servicing revenue. Incentive misalignment was one cause of significant harm to consumers in the mortgage servicing industry. This may also be a contributing factor to the frustration experienced by many private student loan borrowers who submit complaints to the CFPB about payment allocation issues."

According to data from the CFPB and from the Education Department, 40 million borrowers owe about $1.2 trillion in student loan debt. This debt has been shown to delay major life decisions for young people like buying a car, house or having children.

The CFPB is one of multiple agencies conducting their own probe into the lending practices of Sallie Mae and other student loan servicers. They are accepting complaints from borrowers and are willing to help navigate some of the more confusing aspects of student loans.