The New Zealand Government says changes to the Recognised Seasonal Employer scheme, under which thousands of Pacific Islanders work for limited periods in horticulture, will introduce greater transparency.
The Government announced this week that deductions could be made from the minimum wage and that the workers would need to buy health insurance.
But Labour says the move will exploit "vulnerable" workers.
Immigration Minister Jonathan Coleman dismisses the criticism, saying Labour is in an ideological straitjacket.
Dr Coleman says compulsory deductions for health insurance are vital because many of the workers have no cover at all and the New Zealand tax payer "ends up footing the bill."
Now it will incumbent on employers to arrange health insurance, which RSE workers will have to pay for.