Community and Public Sector Union state secretary Tom Lynch said frontline health, education and essential services workforces had been cut to the bone in the past year.

But Mr Lynch has warned there is still more pain to come.

‘‘Tasmanians are already seeing their services being significantly affected and they’re going to see more services significantly downgraded over the next three years,’’ he said.

Unions have rolled out a mainstream and social media advertising blitz ahead of the budget in six days time.

Mr Lynch said $600 million worth of funding cuts to frontline service cuts were embedded over the forward estimates, with hundreds of public servants still facing the axe.

‘‘They’re just simply going to smash services that Tasmanians rely upon every day,’’ he said.

‘‘All these areas that are already under pressure are going to disappear or get worse.’’

Their calls come after it was revealed on Thursday that Tasmania is set to reap a $590 million GST windfall over the next four years.

Unions want funding they say was stripped away under the guise of an alleged ‘‘budget emergency’’ reinvested in frontline jobs and services.

But the state government again ruled out the idea, with a spokesman saying it was important to maintain fiscal discipline.

‘‘Our GST revenue has increased, but it’s temporary,’’ the spokesman said.

‘‘We already know that GST revenue will decline in a couple of years as the economy grows so it’s important that the GST windfall gain isn’t spent on recurrent expenditure that we won’t be able to afford in the future.’’