Tertiary Education Union members are fighting to stop polytechnics reducing the nine weeks of annual leave.
The union says most of the eight polytechs now in pay talks want to change the leave entitlement for tutors.
Suggested changes include converting some of the leave into research or study time, or preventing new employees from getting so many holidays.
These proposals contributed to strike action at Wellington Institute of Technology and Christchurch Polytechnic Institute of Technology in the past week.
The union says core conditions for tutors have been in place for a long time and there is no need to change them now.
But polytechnic managers say the nine week leave entitlement restricts the academic year too much.