NSW Education Minister Rob Stokes has joined Labor and the Greens in criticising the revised Gonski school funding plan.

The so-called ‘Gonski 2.0’ plan has again triggered a funding war between the states and the Commonwealth.

New South Wales argues it will lose $1.8 billion in previously-promised funding.

Mr Stokes says NSW will fight to get that money back at this month's COAG meeting.

“Our message is simple, and consistent — it's been consistent since 2013 which is when NSW became the first state to sign the bilateral agreement,” he said.

“That agreement is now in its fourth year. We remain fully committed to funding the remaining two years of the deal.

“There was an offer; there was an acceptance of that offer, and we've acted in reliance of it.”

Mr Stokes said schools had made staffing and program decisions based on the promised funding.

NSW Labor's education spokesman Jihad Dib agrees.

“Over the last four years we have seen the outstanding results in schools as a result of this needs-based funding,” Mr Dib said.

“Schools know they have less money coming to them, all the plans they'd made are out the window — we've gone too far down the equity road to go back.”