Only children of permitted workers in Melbourne or the vulnerable can access childcare, with the state government hurrying to confirm arrangements on Wednesday night.
The childcare permission will be part of the state's permitted workers scheme, which was to come into force at midnight.
As part of the stage-four lockdown, only workers in permitted industries can travel to their jobs and they will need the signed document to prove their status.
There will be hefty fines for individuals and businesses who breach the scheme rules.
On Wednesday evening, the state government updated online information about the rules around childcare.
"Only the children of permitted workers and vulnerable kids will be able to access childcare and kinder," the website read.
"For the purposes of childcare and kinder, a permitted worker can also include someone working from home."
Earlier on Wednesday, the federal government took steps to guarantee childcare places, centres and jobs as Melbourne moved into its harsh six-week coronavirus lockdown.
Federal Education Minister Dan Tehan unveiled a childcare rescue package before ramped-up measures to shut businesses and severely limit movement take effect.
Prime Minister Scott Morrison said the initiative would secure childcare spots, while ensuring no centres closed or jobs were lost.
The federal government will allow 30 days of extra absences so places aren't lost while children are being kept home.
Mr Tehan said he was confident providers would waive the gap fee for parents.
"For those parents who can't send their children to care, there will be no cost to them. They'll be able to keep their child enrolled," he said.
With the government providing extra payments to providers, Mr Tehan expects centre revenue to be on average between 80 and 85 per cent of pre-pandemic levels.
Victorian Premier Daniel Andrews then confirmed that only permitted workers with no one home to look after children would be allowed to access child care.
He said he could not give the green light to a quarter of a million children going to and from child care each day.
Australian Associated Press