Some 230 Christchurch polytech tutors will take industrial action on Monday against a proposed increase in their hours of work.
The Tertiary Education Union says the polytech is asking tutors to teach for an extra 60 hours a year and relinquish up to four weeks' annual leave.
The union says the tutors at present get nine weeks' leave, which it says helps compensate for the salary cut they take when they turn to teaching.
It says the polytech wants to be able to direct tutors to use up to three weeks' leave for professional development, or to sell up to four weeks' leave for 2% of their salary for each week sold.
The union says new staff will only be entitled to five weeks' leave, which it says will make recruitment difficult for the polytech because its salaries are low.
The tutors will hold a stop-work meeting on Monday where the results of an industrial action ballot will be announced.
The polytech was unavailable for comment on Thursday.