The Inland Revenue Department says it expects about a 100,000 more people will start to pay their student loans off this year.
From the beginning of the month, the IRD changed the rules so that anyone earning salary or wages who has a student loan must add the term SL to their tax code.
The department says about 96,000 people will have to add this code during the 2012-13 tax year.
It says people who are still studying and those who earn below $19,084 can qualify for an exemption.
Last year, total student loan debt amounted to about $10 billion.