Overdue payments to the student loan scheme have jumped by nearly 18 percent in the past financial year to more than $2 billion.
The annual report on the scheme also showed more borrowers failed to make repayments.
The report said 106,000 former students were behind in their payments and nearly 80,000 of them were overseas.
Inland Revenue supported borrowers to keep up repayments during the first years of the pandemic but it was now moving to improve compliance, the report stated.
Altogether, 658,000 people currently have loans totalling $16 billion.
Since the scheme began in 1992, borrowers have repaid $20 billion.
