In Victoria 90,000 workers are being told to apply for criminal background checks.
Workers and volunteers involved with school camps, school crossings, juvenile justice centres and foster care services must apply for a Working with Children Check card by June 30 next year.
If they pass the check, they will get special photo ID cards.
Within five years, more than 650,000 Victorians in 20 child-related fields will have to have police checks and Working with Children Check cards.
Those who do not risk up to two years' jail or a $26,000 fine.
Teachers and police -- already subject to professional checks -- and parents, grandparents and other close relatives who volunteer in activities with their own family members will be exempt.
A $600,000 ad blitz reminding the first group of workers to apply for a card will be launched today.
Attorney-General Rob Hulls said the checks would gradually be extended to pre-schools, kindergartens, sports and social clubs, hospital wards, refuges and religious organisations.
"People who have committed a relevant criminal offence, including child sex offences, or had a relevant disciplinary finding against them will not be able to work with children," Mr Hulls said.
"The checks are subject to continual monitoring, so if a person commits an offence after receiving the card it will be revoked and the employer notified."
He said that over five years the system would be instantly alerted to any child abuse, serious drug or violent crime charges or convictions of card-holders.
The cards will cost paid workers $70, but are free for volunteers.