ITV News video report by Deputy Political Editor Chris Ship
Sickness benefits claimants with chronic illnesses will no longer have to go through reassessments to keep their payments.
Employment Support Allowance (ESA) will continue automatically for those who have lifelong, severe health conditions with no prospect of improvement, Work and Pensions Secretary Damian Green said.
The testing process, which includes reassessing conditions every six months, has come under intense criticism for failing some of the most seriously ill and disabled.
But the reforms will help end the anxiety and financial insecurity that claimants may have felt, Mr Green, who will unveil the plans at the Conservative party conference, said.
The criteria will be drawn up with health professionals but illnesses such as severe Huntingdon's, autism or a congenital heart condition, are among those that are likely to qualify for continuous payments without reassessment.
Mr Green said: "We are building a country that works for everyone - not just the privileged few.
"A key part of that is making sure that all those who are able to work are given the support and the opportunity to do so. But it also means ensuring that we give full and proper support to those who can't.
"That includes sweeping away any unnecessary stress and bureaucracy - particularly for the most vulnerable in society".
Michelle Mitchell, Chief Executive of the MS Society, said: "This is a victory for common sense. Frequent reassessments for people with progressive conditions like MS are too often a waste of time and money; they can leave people with uncertainty and fear of having their support taken away.
“We are therefore delighted that the government have listened to our concerns and have agreed to stop reassessments – albeit for only some ESA claimants."