Charities backing government initiatives such as family literacy and numeracy programmes have warned that the administrative process is also deterring volunteers.
The Criminal Records Bureau waives the pound;12 disclosure fee for volunteers. But umbrella organisations, including education authorities and larger charities, charge fees of pound;3 to pound;25 for certifying applications and documentation.
The National Association of Clubs for Young People, representing 3,000 sports clubs and 35,000 volunteers, is expecting up to 8,000 disclosure requests a year. Reluctantly, it is passing on annual costs of up to pound;80,000 by charging a pound;9.40 administration charge to volunteers.
Colin Groves, national director, said: "Nearly three-quarters of our volunteers are the people least able to pay. It certainly does not help."
The Commission for Racial Equality has asked the CRB to do more to help to people whose first language is not English. From today, all public authorities have a legal duty to promote race equality and produce relevant policies.
The CRB has set up a call centre team able to handle enquiries in 100 languages. Written guidance, including Arabic, Chinese and Urdu, will be available in four to six weeks.
Last week, education ministers intervened to ensure checks on supply teachers were speeded up.