Immigration Minister Iain Lees-Galloway brought his revised proposal on international student post-study work rights to Cabinet and is expected to make an announcement on Wednesday.

Changes to international students post-study work rights could cost the economy $100 million a year, an economist says.

ANZ economist Miles Workman said the "small" loss would result if fewer students came here to study, causing education providers' profits to drop and reduced consumer spending.

International students spent an average of $16,000 a year on fees, worked 20 hours a week and bought goods and services while here, he said.

BEVAN READ/STUFF It will be hard to measure the impact of the Government's post-study visa changes because net migration is already cooling, ANZ economist Miles Workman says.

Roughly 10,000 international students would be affected by the Government's proposed changes, because only half of the international students coming here stayed to work, he said.

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National immigration spokesman Michael Woodhouse said he expected the economic impact of the policy changes to be double Workman's forecast.

GETTY IMAGES National Immigration spokesman Michael Woodhouse says the Government's post-study visa changes could wipe twice as much from the economy than economists expect.

The changes could wipe at least $200m or more from GDP a year, he said.

Workman said $200m was possible.

The amount of uncertainty the proposal created overseas could swing the impact by more than $100m.

His forecast was based on the Government's migration and spending figures and anecdotal evidence from the education industry, he said.

Immigration Minister Iain Lees-Galloway opened public consultation on the proposed changes two weeks ago.

The changes would include removing the employer assisted post-study work visas so international students did not need to be sponsored by a company if they applied to stay here as migrant workers.

Lees-Galloway said dropping that visa was justified because it led to high rates of worker exploitation.

Under the changes, students studying a non-degree qualification, below level 7 had to study for at least two years to be eligible for post-study work rights.

The proposed changes would affect between 12,000 and 16,000 people, Lees-Galloway said.

But, "the fiscal impact should be fairly minimal," because students would be paying for higher-level, more expensive, university courses, he said.

Almost 24,000 international students arrived in New Zealand last year, according to Statistics New Zealand.

Immigration New Zealand granted 7262 employer assisted post-study work visas and 12,474 open post-study work visas last year.

Migration hit a record 72,400 in July last year, according to Statistics NZ. That figure had cooled to 68,000 by March this year.

The post-study work visa changes aimed to make New Zealand look less attractive as a place to study as a means to get residency, which would refocus the export education industry on skills, he said.

Education is New Zealand's fourth largest export earner.