A High Court judge last week ruled that families of severely disabled children must pay the bedroom tax on rooms for carers.
The bedroom tax snatches housing benefit from claimants in council or social housing who have “too many” bedrooms.
Rooms for carers for disabled adults are now exempt from the tax.
Paul and Susan Rutherford launched a judicial review arguing that their 14 year old grandson Warren should have the same right.
Warren requires 24-hour care by at least two people at all times.
But judge Justice Stuart-Smith dismissed the claim. He said it was the job of council discretionary housing payments (DHP) to help families cover the cost of the tax.
The Rutherfords, together with the Child Poverty Action group, have vowed to fight on.
Landlords group the National Housing Federation carried out a survey into those hit by the bedroom tax.
It found that nearly a third had to cut back on food and more than a quarter had cut back on heating.