NSW government agencies will be hit with a further $1.4 billion in cuts in next week's state budget, with Treasurer Gladys Berejiklian set to announce continuation of an annual 1.5 per cent "efficiency dividend".

The cuts will run across the budget forward estimates to 2019-20, but spending associated with schools, emergency services, health frontline services and police front-line services is exempt.

"The victims of our own success when it comes to the GST": Gladys Berejiklian. Credit:Louie Douvis

The standing budget cut, which the government describes as "modest" and targeting back-office operations, has been imposed by the Coalition since it won government in 2011.

It comes despite Ms Berejiklian last year boasting that NSW had the strongest budget in the country, with a string of surpluses forecast across the forward estimates, driven largely by the residential property boom.