WELLINGTON, Aug 9 - PPTA and NZEI Te Riu Roa say 60,000 members will hold paid union meetings next month to discuss the response to the "global budget" proposal.
The unions say they have never undertaken joint meetings on such a scale before - involving principals, teachers and support staff from early child education to secondary.
Bulk funding is "simply another back-door attempt to increase class sizes, which outraged parents when it was last attempted three years ago", says PPTA president Angela Roberts.
"This proposal would result in parents on school boards being forced to do the government's dirty work the moment the budget gets squeezed."
Parents on school boards would have to make trade offs between the number of teachers they employ and other non-teaching costs of running a school.
That would encourage fewer teachers and larger class sizes, increased casualisation of jobs and further downward pressure on support staff hours and pay.
It would also remove the government's responsibility for issues such as class size and curriculum breadth, the unions said.
NZEI president Louise Green says early childhood education and support staff had suffered under a form of bulk funding and extending it would be disastrous.
"The past five years of a per-child funding freeze in ECE have forced many centres to compromise quality by reducing the number of qualified teachers.
"There is no reason to think bulk funding would work any differently in schools."
Education Minister Hekia Parata says the unions have been full members of the funding review from the start, and she was aware of their concerns about the global budget.
"It's entirely up to the unions how they wish to talk to their members and I think it's important that they do."