The National Party is promising to reduce the compulsory student loan repayment rate if re-elected, while cracking down on overseas-based borrowers.

It said it would reduce the repayment rate from 12 percent to 10 percent from April 2027.

The party's finance spokesperson Nicola Willis said compulsory student loan repayments were paid at 12 cents on every dollar earned above $24,128.

"It is often one of the biggest weekly expenses for a young graduate," she said.

''Reducing this to 10 cents means an accountant starting out in their career and earning $75,000 per year would keep an extra $39 a fortnight, or around $1000 a year.''

National would also introduce new financial penalties for borrowers who left the country before paying back their student loan.

That included adding to student loan interest, restricting KiwiSaver withdrawals and making it easier for police to issue arrest warrants for "serious, sustained loan defaults".

Willis said it was not fair for graduates to take their skills offshore after receiving a heavily subsidised tertiary education, and not try to repay their loan.

"Overseas-based borrowers currently account for 93 percent of overdue student loan debt. Only around three in 10 meet their repayment obligations in a given year, compared to 95 percent of New Zealand-based borrowers," she said.

"That is why National will introduce tougher measures to recover student loan debt from people who move overseas."