Almost two-thirds of people affected by the so-called bedroom tax are disabled, according to Citizens Advice Scotland.
A survey also revealed that one in ten of those questioned are caring for a disabled person, while more than half are unable to work.
CAS said it has advised on more than 1600 new issues related to the bedroom tax in the six months since the changes were introduced by the UK Government.
The organisation says that 82,000 households in Scotland are affected by the under-occupancy charge, which sees housing benefit cut for social housing tenants if they are deemed to have a spare room. The organisation’s chief executive Margaret Lynch said, “We have now seen over six months of the bedroom tax, so we have enough evidence to present a real picture of its impact.
“The first thing that is clear is that the majority of Scots affected are sick and disabled people who were already living on low incomes.
“So, like so many of the recent welfare reforms, this is a measure that is principally hitting the most vulnerable people in our society, making their difficult situations even worse.
“Most of the people we have seen are unable to work for health reasons, so were already living in poverty even before this measure came in.
“CAS has recommended that severely disabled people, and families where children have been allocated an extra room due to a health condition, should be exempted in legislation from under occupancy charges.”
The report is published as 40 of Scotland’s leading charities, trade unions and faith groups today launched a campaign to increase benefits to tackle poverty.
Labour’s East Lothian MP Fiona O’Donnell said the system had created “poverty not seen since the 1930s”.
She said she spoke daily to people who are unable to heat their homes, put food on the table and or clothe their children.