Millions of U.S. parents have taken out loans from the government to help their children pay for college. Now a crushing bill is coming due.

Hundreds of thousands have tumbled into delinquency and default. In the process, many have delayed retirement, put off health expenses and lost portions of Social Security checks and tax refunds to their lender, the federal government.

Student loans made through parents come from an Education Department program called Parent Plus, which has loans outstanding to more than three million Americans. The problem is the government asks almost nothing about its borrowers’ incomes, existing debts, savings, credit scores or ability to repay. Then it extends loans that are nearly impossible to extinguish in bankruptcy if borrowers fall on hard times.

As of September 2015, more than 330,000 people, or 11% of borrowers, had gone at least a year without making a payment on a Parent Plus loan, according to the Government Accountability Office. That exceeds the default rate on U.S. mortgages at the peak of the housing crisis. More recent Education Department data show another 180,000 of the loans were at least a month delinquent as of May 2016.

“This credit is being extended on terms that specifically, willfully ignore their ability to repay,” says Toby Merrill of Harvard Law School’s Legal Services Center. “You can’t avoid that we’re targeting high-cost, high-dollar-amount loans to people who we know can’t afford to repay them.”