The U.S. Department of Education’s proposed rules for student loan forgiveness could cost taxpayers as much as $600 billion, far more than the department estimated, according to budget watchdogs.

The Department of Education announced another effort to reduce student debt on Friday. The set of the proposed rulesif finalized, it would authorize loan forgiveness for about 8 million struggling borrowers. If these rules are finalized as proposed, the Secretary of Education could waive the entire outstanding balance of a student loan when the Department determines that a hardship is likely to affect the borrower’s ability to repay the loan in full or to cover costs to continue collecting the unjustified loan.

The Committee for a Responsible Federal Budget, a nonprofit budget think tank, said the plan could cost far more than the Education Department’s estimate of $112 billion over ten years. The front of the group estimate it was up to $600 billion.

“The rules proposed today by the Biden-Harris Administration would offer hope to millions of struggling Americans whose challenges may make them eligible for student debt relief,” said U.S. Education Secretary Miguel Cardona. “President Biden, Vice President Harris, and I will not stop fighting to reduce student debt and create a fairer, fairer and more affordable student loan system for all borrowers.”

Maya MacGuineas, chairwoman of the Committee for a Responsible Federal Budget, called the department’s plan irresponsible.

“The Biden administration continues to unilaterally introduce costly and counterproductive student loans — but this one is particularly unpleasant,” she said. “Today’s rule would essentially give the Secretary of Education unlimited loan forgiveness authority, setting a dangerous precedent that could lead to perpetual debt cancellation.”

The proposed rules would create two ways to eliminate some student debt.

The first path would recognize the authority of the Secretary of Education to grant individualized aid automatically without an application. The Secretary could provide one-time relief to borrowers who the Department determines have at least an 80 percent chance of defaulting within the next two years.

The second route would allow existing and future borrowers to get help based on an assessment of their difficulties. It would be application based. The Department will assess whether a borrower is highly likely to default or experience equally severe adverse and persistent circumstances. If there is no other payment relief option to resolve the hardship, the Secretary could waive the loan.

MacGuineas said the plan could contribute to future challenges.

“Today, the Biden Administration sent a clear message to schools and borrowers: charge as much as you want, borrow as much as you can, and let the grandkids worry about the bill,” she said. “This is no way to run a student loan program or to be good stewards of taxpayers’ money.”