The squeeze is going on Novopay to get a move on with teachers' pay rises.
The NZEI and PPTA unions are taking legal action over the delay in payments.
The cash won't be in teachers' bank accounts until September, despite rises beginning from the start of this month.
NZEI national secretary Paul Goulter says the delay is completely unacceptable.
"We have a duty to our membership to explore every possible avenue to ensure that they get their rights addressed as soon as possible, and that's what we will explore through the legal channels."
The unions have instructed lawyers to file action for urgent compliance orders for payment and for late penalties.
Education Minister Chris Hipkins looked into the situation today.
He says the Ministry of Education and Education Payroll Limited have canvassed options to speed up the process so teachers can get their money sooner.
But he's been advised there are no quick solutions because of the complexity of the payroll and the agreements.
Goulter says that's the Government's problem.
"Been like that for years, we all know about the Novopay disaster. Clearly whatever fixes the prvious Government put in haven't worked and I don't know why teachers should have to be bare the brunt of the failure of that payroll system."
The NZEI and PPTA are filing proceedings seeking urgent compliance orders for payment - and possibly penalties for late payment.