The one-off emergency cash grant, funded by the state government's $650m Jobs Rescue Package, enables those businesses to cover ongoing or outstanding operating costs, like rent and power bills.

Businesses that employ South Australians, have an ABN and were trading on March 1 can apply for the grant.

To be eligible, those businesses must also have a turn over of more than $75,000 and a payroll of less than $1.5 million and not be entitled to the state government's payroll tax waiver under the COVID-19 support measures.

Premier Steven Marshall acknowledged it was a difficult time for employers and their staff who "worked tirelessly to build businesses and a loyal customer base".

"Small businesses are the lifeblood of our community and underpin our state's economy," Mr Marshall said.

"We will do everything in our power to ensure they have immediate support so they have the best chance of getting through to the other side."

Opposition leader Peter Malinauskas backed the state government's announcement, saying the payments would be a welcome boost for thousands doing it tough.

"We know there is a long, tough road ahead for many businesses and much more help and support will be needed," he said.

Business SA's chief Martin Haese said the cash payment would also benefit landlords as well as tenants.

"Many landlords are also small businesses themselves, which is why we have advocated strongly for a financial subsidy for both landlords and tenants," Mr Haese said.

Applications for the grant will open soon and be available until June 1.

Australian Associated Press