The WA Education Department is preparing to slash up to 800 full-time jobs by March next year, in a move unions claim will devastate the public school system.

The job losses are part of the WA Government's Voluntary Targeted Separation Scheme (VTSS) announced by Treasurer Ben Wyatt when he handed down his first budget in September.

The scheme aims to cull 3,000 public sector jobs by March 2018, and it has emerged 800 of those positions will come from non-frontline education roles — teachers and teacher assistants will not be affected.

State School Teachers' Union president Pat Byrne said with school-based personnel quarantined from the scheme, the job losses would come entirely from a pool of 1,200 non-school-based staff.

"This cut will decimate the department's school support services, central and regional offices, the Institute of Professional Learning, and have a serious impact upon WA schools," Ms Byrne said.

"Cuts to staff numbers of this magnitude are unfairly disproportionate and simply unsustainable.

"These moves will directly impact upon frontline schooling with principals and teachers being unable to access the support they need."

Minister won't rule out forced redundancies

Education Minister Sue Ellery yesterday issued a statement ruling out forced redundancies, but refused to repeat this assurance when questioned further today.

The union claims services to schools will be affected by the cuts. ( ABC News )

"We know so far after asking staff who are interested, nearly 300 [education staff] have said, 'yes they're interested,' but we have to work through whether any or all of those who've expressed an interest are the right ones to go," she said.

"I can understand that there's a lot of chatter about how we get there and a lot of uncertainty and I do want to reassure people and reassure staff that this is not about any forced redundancies."

Ms Ellery wouldn't say what would happen if her department fell short of reaching its redundancy target.

"That's hypothetical, we're not there yet," she said.

"I'm not going to second guess where we might end up at the end of March next year.

"All government agencies need to find savings within their existing budgets and, like other agencies, the Department of Education is currently working through the state's voluntary targeted separation scheme."

Cuts a 'body blow' for WA education

CPSU/CSA branch secretary Toni Walkington said her members had been betrayed.

"To say we are disappointed is an understatement. We are outraged," Ms Walkington said.

"This is a body blow for WA's education system and extremely disappointing from a government elected on a jobs platform.

Toni Walkington and Pat Byrne (l-r) do not believe the cuts are sustainable. ( ABC News: Rebecca Carmody )

"We already know that employees engaged on contract providing important services will be gone at the end of this year, raising serious questions about how services to schools will be delivered once the redundancy process is completed.

"The targeted staff provide a range of valued services for principals, teachers and students such as professional learning, support for students with special needs and for teachers and schools dealing with severe behaviour issues."

Before the election Labor promised there would be no forced redundancies under its watch, but last week Treasurer Ben Wyatt appeared to backtrack, stating he would not rule any contingencies "in or out" in the event of a shortfall.

Unions claimed some support staff had been pressured to apply for voluntary redundancies and told if they did not go willingly, they could be forced out.

"If 100 out of 800 people put up their hand that's fine, but that means that 700 people are still going to be targeted and they're going to be forced into redundancy," Ms Byrne said.

"That's not fine and in fact it's downright dishonest."