Mencap, and a number of other charities, are launching a campaign against the 'bedroom tax' which is due to come into force next month.
They say disabled people should not be discriminated against, and that disabled families need to be exempt from the 'tax', because they need an extra room to meet their needs.
The 'bedroom tax' will affect around 660,000 social housing tenants across the country.
The under-occupancy charge sees housing benefit payments reduced for tenants in council or housing association properties with empty bedrooms.
More top news
British hopes for a sunny Easter break have been dealt a blow with forecasters warning of a week of wind, rain and even snow.
More than one in five school staff have had a false allegation made against them by a pupil, according to a survey.
Parents of obese children rarely spot that their child is overweight, doctors warn.