Under new Government rules, they will need a certificate from a new Criminal Records Agency, giving details of convictions, or showing they have a clean record.
Civil liberties groups said that while people working with children should be vetted, they fear "spent" convictions appearing on the certificate could prejudice a person's career prospects.
The new rules are contained in the Police Act 1997. Although it is Conservative legislation, it was supported by Labour and the Home Office has now set up a consultative group to advise on bringing in Section V of the Act which introduces the certificates.
Sarah Veale, TUCsenior policy adviser and a member of the Home Office group, said: "We will be calling for the Government to exempt people like teachers and social workers, who are not high earners, from the payment."
The Act does not make it clear whether it would be the teacher or the school who picks up the bill. Teachers will also be expected to pay Pounds 10-20 to register with the General Teaching Council when it is set up.
Paul Cavadino, principal officer of the National Association for the Care and Resettlement of Offenders, said: "It is right that people employing those who work with children have full information about their background. But they should only have relevant information, and do not need to know about convictions that do not pose a risk to children."