A charity has warned that changes to Disability Living Allowance could be “devastating”.
The National Autistic Society said they have “serious concerns” that the new face-to-face assessments may not be relevant or accessible to adults with autism.
The charity said the less visible difficulties of people with autism can be hard to understand for assessors who are not specialists.
A new report from a coalition of disability charities said there has been a £500m drop in disability support since the Budget of 2010, and said 500,000 disabled people were "expected to lose out" when the Disability Living Allowance was scrapped.
Mark Lever, Chief Executive of The National Autistic Society said:
“The findings of this report are alarming, but sadly unsurprising. We frequently hear from people affected by autism who are worried about what the future might hold once disability living allowance is withdrawn.
“The effects on those who lose out could be devastating. Three quarters of people with autism surveyed said that without DLA or PIP they would not be able to manage their condition and a further 85% with the disability said that they would be left isolated.
"In these financially straitened times, it seems particularly wasteful to subject people with lifelong disabilities such as autism to constant reassessment when their condition is not going to change.
“When the welfare reforms were originally debated, the Government committed to ensuring all assessors were fully trained to recognise the needs of disabled people. The Government must uphold its promise, or it will it betray some of the most vulnerable people in society.”
The Government plans a new work-capability check for disabled people.
The assessments, which will see Personal Independence Payments replace Disability Living Allowance, will start next year. Up to two million people will need to be assessed for PIP.
Jaspal Dhani, CEO of the UK Disabled People's Council (UKDPC) and co-chair of the Hardest Hit campaign, said:
"Disabled people, those with long-term conditions and their families are already at risk of hardship and face massive barriers to getting into work and education. Cuts to the support they depend upon risk pushing them into poverty, debt and isolation.
"The Chancellor has just announced a further £10 billion cut to the welfare budget. With £9 billion having already been removed from disability benefits and services in this Parliament, disabled people are already at a tipping point. The Government has some urgent choices to make, but must rule out targeting disabled people for further spending cuts in the next Budget and Comprehensive Spending Review."