The Accident Compensation Corporation has trimmed allowances for workers who provide home care for its beneficiaries.
Their union, the Public Service Association, says ACC has reduced the amount it will spend on reimbursing travel expenses, to save money.
The union says refunds have been given in the past for an entire journey if the workers travelled more than 20km to a job.
In future, they will be reimbursed only for mileage above 20km.
ACC says the change brings it in line with the policies of other agencies and treats the workers in the same way as most other employees.