Treasurer Daniel Mookhey and the Minns government will deliver their first budget on September 12.
It comes after Mr Mookhey identified $7 billion worth of unfunded programs and unavoidable pressures during treasury briefings, which needed scrutiny.
He said delivering the realigned budget outlook for 2023/24 would take an additional three months to the September date.
"We face difficult choices ahead as we make sure the public's money is spent on the public's priorities," Mr Mookhey said.
He said the government did not intend to make cuts to the state's budgets, instead intending to go through spending "line by line".
The parliament has also set aside 12 days for budget estimates hearings in October.
The new schedule for the NSW parliament has also been revealed, with politicians expected to front up to the Macquarie St building as often as they did before the COVID-19 pandemic.
MPs will sit for 39 days across 13 of a possible 34 weeks remaining this year, excluding the week of Christmas.
The parliament also reserves a week in December for extra sittings.
