The state government registered a $70 million increase to its budget for consultants last financial year, spending that is now double levels reported four years ago.
The government ended up spending more than $200 million on external advice last year compared with a budget of $135 million, according to updated budget forecast figures.
It is the fourth year in which the Coalition government has exceeded its budget for external advice. In 2013-14, the government overshot by about $60 million.
Ironically, much of the blowout came with a $50 million bill accounted to the state's Crown Finance Entity, which is responsible for keeping charge of the state's liabilities.
But the Treasurer's office said that spending was due to the costs incurred in advising the windfall sale of the state's electricity assets, which could not be included in forecasts because they were commercially sensitive.
Other agencies such as the Justice and Education departments racked up smaller bills but which still more than doubled their budgets.
"Taxpayers expect the government to be making the decisions that run the state," said the shadow treasurer Ryan Park. "Premier Mike Baird should be focused on fixing the ongoing issues in these departments. Instead they have been flicked to the private sector."
But Finance Minister Dominic Perrottet said the spending was commensurate with the growing list of projects the government was undertaking: "By its very nature, major government reform often calls for expertise that isn't held within the bureaucracy, and it would be irresponsible for the government not to get that advice."
Spending on consultants now exceeds that of many smaller government departments, such as the state's emergency services, which run to an annual budget of less than $100 million.
The state government has promised to make its spending on consultants more transparent and accountable with reforms it projects to save taxpayers $45 million and to make state government agencies less dependent on external advice.
Consultants have had a role in making the government's case for several major projects.
The investment firm JPMorgan will be paid just less than $5 million by the state government to advise on the sale of its land titles office.
Elton Consulting, meanwhile, was handed $2 million to design a curriculum for Sydney school students to teach them about how a government rail project was "changing their [community] for the better".
The figures come as the state government has been revelling in good financial news. Updated accounts figures show the government clocked up a budget surplus last financial year of $4.7 billion. That was $1.3 billion more than was forecast in June, when the Treasurer delivered the budget.
State government agencies were hit in June with a $1.4 billion cut to their spending over coming years through an ongoing "efficiency dividend" that obliges the agencies to reduce their spending each year.
