The leader of the Liberal Democrats is proposing that anyone with a house worth more than £1m should pay an annual levy.
The money would be used to raise the income tax threshold to £10,000.
Liberal democrat leader Nick Clegg explained the proposals in an interview on the Today programme, saying that the move was necessary to correct "one of the most unfair tax systems around."
"This is a small correction which I think will make a big difference for people who are really struggling to make ends meet," he said.
He also defended his comments that "savage" cuts to public spending would be needed, saying that it was "simply wrong" for the Conservative and Labour parties to avoid using "the c word".