NSW's net debt will be wiped out following a bumper budget surplus of $4.7 billion this financial year, Treasurer Gladys Berejiklian says.

The healthy result for 2015-16 is a $1.3 billion improvement on the $3.4 billion surplus flagged in the June 2016 budget.

General government sector net debt fell from $5.5 billion at 30 June 2015 to negative $57 million at the same time this year – meaning NSW is in a cash positive position for the first time on record, she said.

“Our fiscal discipline and asset recycling strategy has allowed us to invest record amounts on infrastructure while securing our triple-A credit rating,” Ms Berejiklian said.

“This unprecedented infrastructure program is also supporting our booming jobs market, solid housing construction industry and helping to boost consumer confidence and business investment.”

The state’s coffers have been benefiting from a windfall revenue from property taxes, fuelled by Sydney’s booming property market, as well as the the recent $10 billion sale of electricity network TransGrid.

The Baird government’s debt-free days will be short-lived however with spending on big infrastructure projects such as the WestConnex motorway and the Sydney metro rail project set to ramp up over coming years.