The South Australian Council of Social Service says it's concerned many vulnerable and disadvantaged South Australians will miss out on the benefits.

While Business SA says the budget lacks tailored support programs to help those companies hardest hit by the COVID-19 pandemic.

Releasing the budget on Tuesday, Treasurer Rob Lucas forecast a deficit of $1.39 billion for the next financial year before a return to a modest surplus of $48 million in 2022/23, a year earlier than previously projected.

The surplus is then expected to grow to $498 million the following year.

The SA economy is tipped to grow by 3.5 per cent in 2021/22 and then by 2.25 per cent each year across the forward estimates.

Mr Lucas has confirmed a $17.9 billion infrastructure program across the next four years including more than $800 million for road projects and cash to start planning for a new sports stadium in Adelaide.

The budget focuses heavily on health, with $163.5 million for increases to mental health facilities and services, more money to increase capacity in hospital emergency departments and funds to help ease ambulance ramping.

It also confirms the proposed new Women's and Children's Hospital will cost $1.95 billion with the first patients expected to be admitted in 2027.

Education is similarly a winner with cash for a new high school in Adelaide's eastern suburbs and $50 million for an early learning strategy to increase early intervention and child development health checks.

But Business SA chief executive Martin Haese said the largesse offered small to medium business owners very little peace of mind should SA find itself in another pandemic-induced lockdown.

"Unfortunately, the budget lacks tailored support programs for hard-working business owners that have borne the brunt of seismic uncertainty over the last 15 months," he said.

"This support is the recipe for addressing unemployment and under-employment across many industries."

SACOSS chief executive Ross Womersley said while some of the budget measures were welcome, including extra funds for mental health, there were missed opportunities.

"Overall, our key message is that we would like to see more action over the coming months to target assistance and support to those most likely to be struggling so that as we move towards a post-COVID recovery, people are not left behind," he said.

Australian Associated Press