The Biden administration’s efforts to forgive hundreds of billions in student debt stymied by the Supreme Court, it is turning to major overhauls of existing student loan programs that could cost as much as half a trillion dollars over the next decade, according to a new analysis released Monday.

Analysts at the Penn Wharton Budget Model at the University of Pennsylvania say new rules formalized last week by the Department of Education for President Biden’s income-driven repayment plan — under which loan repayments are based on borrowers’ income and family size — will cost American taxpayers as much as $475 billion over the next decade, more than three times what the administration previously said it would cost.

The previous analysis of what the Biden administration is calling its Saving on a Valuable Education plan by Penn Wharton estimated that the program would cost $361 billion over 10 years. When the plan was announced, the Department of Education promised the program would cost taxpayers no more than $138 billion, and the Congressional Budget Office said it would cost no more than $230 billion.

In a statement announcing the plan, the White House pledged that the amount borrowers will have to pay monthly relative to their income will be cut in half under the new plan and that all outstanding balances will be forgiven after 10 years of payments instead of the 20-year timeframe under the current program.

“No President has fought harder for student debt relief than President Biden, and he’s not done yet,” the White House statement said. “President Biden and Vice President Harris will not let Republican elected officials succeed in denying hard working Americans the relief they need.”

The Penn Wharton analysis says some $200 billion of the costs of the new program are likely to come from reduced payments on more than $1.6 trillion in already outstanding student loans. About half of current loans are likely to be shifted over to the new program when it goes active in July 2024, suggesting that about $869 billion in student loans already on the books will be eligible for new taxpayer-financed subsidies, according to the analysis.

The remainder of the total price tag, or about $275 billion, comes from reduced payments on more than $1 trillion in new loans expected to be made over the next decade. Penn estimates that about 70 percent of student borrowers will take advantage of the new program. More than 6.5 percent of those new borrowers will probably never have to make any payments on the debt they take on to pay for college.

Under a deal cut last month with Speaker McCarthy to resolve the standoff over the debt ceiling, payments on millions of existing student loans — which have been paused for three years now — will resume August 30. That pause has cost taxpayers an estimated $210 billion.

An analysis of Mr. Biden’s plan by the liberal Urban Institute in January said the new program will encourage students who currently are not borrowing to pay for their education to take out new and larger loans because the amount they will be forced to repay over time is the same, about $957, for a $3,000 loan as it is for a $12,000 loan.

“This may be particularly salient at community colleges, where nearly half of students currently do not take on any debt,” the analysis says. “Under the Biden plan, these nonborrowers may find that they can take out a loan and expect to repay only a small percentage of it.”