Sixteen plum directors' jobs at the NSW Treasury are currently being advertised, Fairfax can reveal. Directors command salaries of up to $230,000 a year.

The vacant positions represent 15 per cent of the department's senior directors, according to 2015 figures.

The department is also looking for a chief of staff on a salary of up to $290,000.

The vacant directors' jobs, which are three rungs below Treasury Secretary Rob Whitfield in the department's pecking order, have a combined salary of up to $4 million a year.

Treasury spends about $20 million on remunerating its top executives.

Labor's shadow Treasurer, Ryan Park, said the vacancies suggested dysfunction in the department.

"Millions of dollars been spent on more senior public servants whilst every other Government department is been told to rein in their costs," Mr Park said. "If a big bank or large corporation did this it usually means that something is seriously wrong with the organisation".

But the state's Treasurer, Gladys Berejiklian, said the changes reflected restructure and renewal in a department meeting "enormous opportunities".

"This has led to some people being promoted, others moving to different roles and a number leaving Treasury," the Treasurer said. "These changes boost Treasury's skills and capabilities so that it can [support] a modern government."

The staff changes come after Mr Whitfield, a former top Westpac banker, was appointed to the department's top job last year and as it faces a plummeting share of GST revenue, a drop that amounts to more than $10 billion over the next four years.

Mr Whitfield's base salary is about $550,000 a year, with the potential for performance bonuses. It's a fraction of the $5 million a year he was earning at the bank.

Treasury has imposed a $1.4 billion cut to government departments' budgets in coming years with an "efficiency dividend" that forces them to reduce their spending each year.