One Nation could be forced to run policies by the budgeting office before a state election - a move already unpopular with the crossbench.
The NSW government and opposition are required by law to submit their proposals for independent costing.
But Treasurer Daniel Mookhey on Monday said he would seek to have One Nation NSW additionally required to submit its platform to the Parliamentary Budget Office.
That office would then create a budget impact statement for all three parties before voters head to the polls.
The change is recognition three parties will credibly compete to form government, Labor stated, and the office would be additionally resourced in line with added demand.
"Voters deserve to have independent advice about what they mean for them," Mr Mookhey said.
"NSW can't afford to live in budget fantasy lands, especially when economic conditions are so uncertain."
One Nation NSW intends to stand candidates for all 93 lower house seats and continues to perform well in NSW and federal polls, despite currently having no sitting MPs.
DemosAU’s end-of-August survey of 1028 residents had One Nation running third on primary vote intention (23 per cent) to the coalition (25) and the Labor government (32).
The government will need the assistance of the Liberal and National parties to pass the costings changes.
NSW's Greens will not support the amendment, arguing it gave One Nation undue credibility.
Greens MP Abigail Boyd said Labor was playing politics with precious public resources.
"Causing One Nation policies to be costed will show them to be half-baked, destructive and guaranteed to backfire on the people of NSW - we all already know this to be true," she said.
"But Labor are asking the voters to compare them to One Nation, rather than compare them to a party like the Greens."
AAP contacted One Nation's NSW leadership for comment.
Mike Newman and Stuart Bonds previously told AAP they wanted to halt the state's public service growth, slash business restrictions, and freeze GST increases.
Repealing the state's net-zero commitments and accelerating coal and gas approvals are core to their energy agenda.
Both leaders have also floated proposals surrounding abortion laws and scaled-back police body-cam usage.
One Nation's Victorian arm faced scrutiny for the release of a 64-page policy document with no costings.
