People who volunteer in schools and clubs in England and Wales will no longer need duplicate checks on their background, ministers have confirmed.
They will be able to have a new "portable" background check, which they can update for free.
At the moment, a person who has been screened to volunteer in a school needs to have a separate check before helping out a different group.
Voluntary groups have welcomed the move.
They say cutting red tape will be "a huge boost" which will encourage more people to come forward.
The changes also affect people who need to be vetted for their jobs, such as doctors and agency workers, who often need new checks when moving posts or changing agencies.
It is part of other changes brought in this year aimed at simplifying the system for vetting people who work or volunteer with young or vulnerable people.
Home Office minister Lord Taylor said the changes would cut bureaucracy and costs for millions of people and organisations.
"The government is committed to reducing barriers to volunteering whilst helping to protect vulnerable groups," he said.
"It is a 21st century service that will deliver real benefits without compromising on public safety."
Officials say last year more than four million people applied for a criminal records check and that about a quarter of those were volunteers.
About 10% of people applied for more than one check.
Checks on people who work with young people are a key pillar of child protection, but have not been without controversy.
A portable and free background check on individuals should cut the bureaucracy involved with volunteering.
It is part of a shift set out in the Protection of Freedoms Act which became law in May this year.
Labour tightened the rules on the vetting of people who come in to contact with children in schools and clubs in 2009 after the murders of Jessica Chapman and Holly Wells by school caretaker Ian Huntley in Soham.
Authors such as Philip Pullman complained they were being asked to pay for what they saw as over-zealous checks when they wanted to visit schools.
The coalition government relaxed some of the rules on coming to power, leading some to say it was a victory for common sense and others that it was an erosion of vital safeguards for children.
In seven years, 150,000 unsuitable people have been stopped from working with vulnerable groups, the government said.
The new system will involve what is called an "update service", run by the Disclosure and Barring Service (DBS), which has replaced the Criminal Records Bureau (CRB) and the Independent Safeguarding Authority.
Volunteers will need to apply on paper for a certificate to show they have had a criminal check and after that can give permission to a group they want to volunteer with to go online and check whether that the certificate is still valid.
If there have been any changes, the group will not be told what they were, officials say, but will be told another paper application is needed.
There is a cost for the existing background checks (up to £44) but voluntary groups and volunteers are exempt.
The new updates will be free, the government said, although voluntary groups will have to pay an annual subscription.
Chief Executive of Volunteering England Justin Davis Smith welcomed the changes, saying they would boost volunteering by "cutting red tape".
"We are delighted and relieved that the home secretary has listened to the concerns raised by volunteer-involving organisations by ensuring all aspects of DBS checks remain free to volunteers," he said.
"This is particularly significant when charities and public services are looking to sustain the enthusiasm for volunteering created by the Olympics and Paralympics."
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