I would make it a 'complete, long term non-occupancy' tax, that is solvable by renting the places out or having someone live in them. People can still have whatever space they want, but don't do the utter waste of buying a house as a another form of bank account.
But as we all know getting bureaucracies to implement something like this will cost hundreds of millions, and will it be beneficial in the short term? Probably not. But we should start looking at long-term solutions.
> Michael Rosen writing in The Guardian has criticised how, under government proposals, parents living in social housing could become liable for what he calls the bedroom tax after only three months following the death of a child – something that inadvertently causes the creation of a "spare" room.[26] In March 2015 the Daily Mirror, a British tabloid newspaper, reported that a woman had become liable for the bedroom tax following her son's death from a brain haemorrhage following an assault.
> The changes in housing benefit have been criticised for having a disproportionate effect on disabled families. Two-thirds of individuals affected by the under-occupancy penalty are registered as disabled.
Source: https://en.wikipedia.org/wiki/Under-occupancy_penalty
Penalizing people for having extra rooms while it is impossible for them to downsize because there is insufficient supply of smaller properties is not a long term solution.
http://www.independent.co.uk/news/uk/politics/big-lie-behind...
The main problem is the lack of correct sized social housing. The bedroom tax forced people to downsize.
In southwark the most pressure of housing is for one and two bedroom properties. Most people were downsizing from 3+ into 2 or 1 bedroom places.
If the price is too high, its not because of tax (3-5%) its because there isn't enough to go round.
The lack of state rental housing means that there is increased pressure on private rental. There is no new supply of rental housing, which means that the existing stock becomes more valuable. This means that rental prices rise inline with the value of the housing stock.
This is turn means that the direct cost to the government rises as well.
Its literally cheaper to build council houses.
However this will never happen because: 1) it involves borrowing money for the "poor"
2) it involves planning for something longer than two years
3) it will lower house prices for the very voters that got the tories into government.
Nothing will change untill a crisis happens. And by crisis I mean the voting classes getting impacted.