as far as I understand it, it is not a tax, rather a reduction in benefit if you claim for housing benefit and council tax benefit, and you have under-occupancy (in the government's opinion) of bedrooms. It does not seem to matter if a couple sleep separately because of various reasons eg medical necessity.
It takes no notice if you are already asking to be re-housed in a smaller house or flat, and one cannot be found.
It takes no notice if you have lived in the property for many years and have ooodles of memories connected with it.
It takes no notice that you cannot afford to buy your own home.
DC - #that will teach the poor to be poor#
I know it is not a quote from DC, but people of his ilk will definitely have thought it.