Sydney drivers slugged with spiralling road tolls will get some relief in the upcoming state budget, ahead of new price rises next month.
A 40 per cent rebate will be available for toll road users, including tradies, who spend more than $375 a year on tolls, up to a maximum of $750.
"It's the most significant support when it comes to toll relief for families in the history of the state," Premier Dominic Perrottet said on Tuesday.
The cashback program, part of the June 21 budget, will replace a scheme giving drivers subsidised or free vehicle registration depending on their yearly toll spend.
While that scheme will end on July 1, Mr Perrottet says drivers can still benefit for one more year because it's based on the previous financial year.
Treasurer Matt Kean said the new rebate would benefit about 300,000 more drivers than the existing registration scheme, at a cost of $520 million over two years.
"This is a small price to pay to ensure that more motorists can benefit from cash back into their bank accounts," he said.
Small businesses and tradies will be eligible for toll relief under the rebate, but heavy vehicles remain excluded.
Metropolitan Roads Minister Natalie Ward says the government wants to encourage people to use the tolled motorway network.
"By getting people on the motorways we get them across the network quickly, reliably and more efficiently, but more importantly, get them out of sitting in traffic and back home to their families," she said.
ServiceNSW will manage the rebates, which will be paid quarterly.
Drivers who apply for an existing cashback scheme on the M5 in Sydney's southwest won't be eligible.
For the registration scheme, private drivers will have to spend $877 on tolls to halve their rego cost and $1462 to make it free for the last year of the scheme.
Opposition Leader Chris Minns said the government was trying to curry favour with drivers in Sydney's west before the March election.
"This is a bandaid solution for a broken system that Dominic Perrottet created," he said.
Labor has not announced alternative relief and Mr Minns said any policy before the next election would have to abide by contracts already entered into with the toll road operator.
Mr Minns said the privatisation of state assets had driven up costs and robbed the government of leverage in negotiations.
But Mr Perrottet said privatisation had allowed the government to invest more in road infrastructure and toll relief could help when it comes to negotiations with the operator.
"This is an indication of where I believe a fair pricing system should be based and I think that kind of lays the foundation and the platform to go into the negotiations."
Mr Perrottet also wants to remove flagfalls levied on drivers for moving on to a different motorway.
While the privatised assets are gone, Mr Minns has vowed to protect the remaining electricity, rail, and water assets if elected.
"If the government is re-elected they will be tempted to sell off because ultimately the premier has never accepted that privatisation as an ideology has put taxpayers second and private companies first," he said.
Mr Perrottet told parliament on Tuesday Labor left behind a $30 billion infrastructure backlog when it lost government in 2011.
"We make no apologies for building the motorway network, for building the roads and the public transport networks that set up our state for success," Mr Perrottet said.
A government review of the state's tolling regime is under way.
Toll road costs are due to rise next month, after last increasing in April.