To improve children's safety every effort should be made to expand the number of cases where police vetting is used, Ms Roberts said. Charging for the service would likely lead to a drop in demand.
"The problem when you shift that cost to schools, or the teachers within those schools, or the soccer coaches within those schools, is you actually add to the inequity issues that we have in this country.
"Our most vulnerable children in the most vulnerable communities are less likely to be able to resource the police vetting that is required, or desired."
Ms Roberts said the charges would probably not be any issue for private or high decile schools or people working with them.
"But if you are a soccer coach in a decile one school it is probably going to a little more difficult for that school community, whether it is the parent or the school themselves, to meet those costs.
"Our vulnerable communities are going to be hammered."
Asked whether a charge of around $7 would be a big financial strain, the PPTA said it feared charges could rise in the future.
Comparable regimes in Australia charged between $30 and $52, the union stated.
"And it's not actually how much the cost is...the point is, it is a public good," Ms Roberts said.
Ministers have promised that vetting will be the only service to incur a charge.
The Police Association has said its members supported moves to reduce the strain on the frozen police budget but believed cost recovery should be limited to private commercial interests.
The Policing (Cost Recovery) Amendment Bill would give powers to the minister to make exemptions but it's not yet clear how these will be used.
Criminal checks
• Between 450,000 and 500,000 criminal checks a year
• Estimated cost to police of $2.2 million
• Some organisations, such as those that work with children, legally required to vet staff
• Government wants to charge $5 to $7 for checks.
