Owners of homes worth over £2 million could be hit with a new levy based on council tax bands under the Liberal Democrats' revised proposals for their flagship "mansion tax".
Lib Dem Treasury Chief Secretary Danny Alexander said that the party would seek to impose a "modest additional banded levy" on top of council tax for high value properties if it was in government after the next general election.
Speaking in the City of London, he said the charge would be collected through local authorities in the same way as the council tax, but that the proceeds would go to the Exchequer.
"The annual charges, in addition to council tax, will be set out in good time ahead of the general election next year," he said.
"By building on the council tax system, there will be no need for a detailed valuation of the small proportion of properties affected. Crucially this means that this policy could be implemented quickly after the election."
Mr Alexander said the blueprint had been drawn following modelling and analysis in the Treasury to establish how the policy could best be delivered.