More than 40% of Americans who borrowed from the government’s main student-loan program aren’t making payments or are behind on more than $200 billion owed, raising worries that millions of them may never repay.

The new figures represent the fallout of a decadelong borrowing boom as record numbers of students enrolled in trade schools, universities and graduate schools.

While most have since left school and joined the workforce, 43% of the roughly 22 million Americans with federal student loans weren’t making payments as of Jan. 1, according to a quarterly snapshot of the Education Department’s $1.2 trillion student-loan portfolio.