The Minns government will amend the law governing the Parliamentary Budget Office (PBO), which currently provides costings only for Labor and the Coalition in the lead-up to elections. The change would give One Nation the same access, a move the government says is necessary because the coming election is likely to be a three-cornered race in many electorates.
Treasurer Daniel Mookhey laid down the challenge, saying the state "can't afford to live in budget fantasy lands".
"One Nation has made no secret of how much they admire American and Argentinian-style wage policies, healthcare policies and cuts to the public service," he said. "No doubt they will want to import these ideas into NSW, but voters deserve to have independent advice about what they mean for them."
The independent PBO was established before the 2011 election and traditionally releases costed budget statements for both major parties days before polling, providing a final test of fiscal credibility.
One Nation currently holds no seats in the NSW Parliament, but Labor has increasingly focused on the party as repeated polls show Labor leading the Coalition on primary vote. The amendment is seen as a recognition that One Nation could hold the balance of power or influence the outcome in key seats.