This is more than half of the $1.3 billion budget surplus forecast by Treasurer Ben Wyatt to be on the books in 2020-21.

While every other jurisdiction has costed and set aside money for their participation in the scheme, WA risks lagging behind.

This week, South Australia joined the scheme, sinking into its coffers $146 million from its victims of crime fund.

New South Wales has already introduced legislation to formalise their participation.

Meanwhile, there is no money set aside in WA's budget.

Mr Quigley's office said last night the scheme had not been scrutinised by the government's powerful Expenditure Review Committee as part of the last budget process because it was not yet at an "appropriate stage of development".

However, the budget papers do identify the scheme as a risk to the bottom line.

"Should the state choose to provide access to a redress scheme, a provision will be required that will have an impact on the state’s financial aggregates," it read.

That's an understatement, especially if Mr Quigley is right about how much it will cost.

Cost and fine print aside, Mr Quigley conceded survivors may be disadvantaged if the state fails to sign up by the start date.

"But I'm asking everyone to trust me that I'm working hard and negotiating very hard in the interests of Western Australian survivors," he told ABC radio.

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"I am confident of nailing this."

Mr Quigley insisted the state was not prevaricating.

There are thousands of Western Australian men and women who survived horrific crimes while in state institutions.

They will be counting on the government – and Mr Quigley – to get the job done.