SA Treasurer Tom Koutsantonis will slash 750 public service jobs to pay for his defeated bank tax, and will sacrifice future surpluses to cover a raft of new spending in the lead up to the March state election.

The Treasurer's mid-year budget review — the last glimpse of the Government's books before polling day — foreshadows $370 million in savings over the next four years, which is the same amount the blocked bank tax was set to recover.

Budget review at a glance 750 public service jobs to go

750 public service jobs to go Future surpluses revised down

Future surpluses revised down Privatisation to help reduce debt

Privatisation to help reduce debt About $500m new spending on health and disability

About $500m new spending on health and disability Commercial care for vulnerable children to cost more

That adds up to a net reduction of 263 public servants, plus further reductions in government-run corporations SA Water and the Urban Renewal Authority.

A third corporation (Homestart) will be spared the job cuts but has been forced to deliver 100 per cent of its 2016-17 and 2017-18 profits to the Government, up from the usual 60 per cent.

Mr Koutsantonis said frontline services like police, nurses, doctors, teachers, ambulance officers and firefighters would be quarantined from the cuts.

Contrary to savings measures in recent budgets, Mr Koutsantonis said it would be left to departmental chief executives to find savings from their own back-office functions.

"We've given them the flexibility to either close programs and reallocate people, offer some targeted separation packages, maybe not recruit against attrition in some areas," he said.

"So it's not necessarily job losses, it's just natural attrition.

"The accurate way of looking at this is we're giving maximum flexibility to our chief executives to deliver these savings in a way that will do the least amount of harm."

Public Service Association official Neville Kitchin said jobs were under siege and some administrative work was likely to be pushed onto front line workers if backroom positions went.

"The public service has already been cut to the bone," he said.

Mr Kitchin questioned the Government's level of consultant hiring in the public sector.

"If they're looking for efficiency dividends, as has been identified in recent reports, then they could actually start trusting people within government to do their roles, rather than hiring so many consultants and [seeing] millions of dollars being wasted in those particular areas," he said.

Surpluses slashed, debt down, GST revenue up

The Government delivered a bumper $443 million surplus for the 2016-17 financial year — $204 million higher than expected at the June budget.

That was thanks in part to the privatisation of the Motor Accident Commission, a dividend from SA Water and delayed spending.

But forecast surpluses over the next four years have been revised down by $388 million. This year's forecast surplus has been slashed from $72 million to $12 million.

An unexpectedly high $1.6 billion windfall return from the privatisation of the state's Lands Titles Office has allowed the Treasury to wipe more than $1 billion of government sector debt.

But debt across the government sector and corporations like SA Water is forecast to climb over the next four years.

GST revenue has been revised up $348 million over the next four years.

Property and gambling taxes have been written down by $269 million, but improving employment prospects will see an additional $40 million in payroll tax collected.

The SA Opposition said the Government was failing to achieve jobs growth.

Liberal treasury spokesman Rob Lucas said South Australia's employment growth was expected to be 1 per cent this financial year compared with a national figure of 1.75 per cent.

"We're going to continue to trail jobs growth nationally with the continuation of the policies outlined in the budget, and further implemented in the mid-year budget review," he said.

Health, children in care dominate new spending

A failure to recruit enough foster carers will mean the Government will have to pump another $159.1 million into the child protection system, mostly to pay for residential and commercial care for vulnerable children.

That is in addition to an extra $518 million spent on the child protection system since the release of Margaret Nyland's royal commission report last year.

Another $467 million will be spent on additional services in the state's hospitals, with some of that spending pumped into the recently opened $2 billion new Royal Adelaide Hospital.

An additional $96 million will be spent on demolishing, remediating and preparing the old Royal Adelaide Hospital site for development, after a deal with a private sector developer collapsed.

Moves to boost the flagging fortunes of the Adelaide 500 car race, including big headline concert acts Robbie Williams and Cold Chisel, are set to cost the budget an additional $9.6 million over the next four years.