Ministers are this weekend examining steps to ensure the new property tax won't discourage people from extending or refurbishing homes.
Under the proposals homeowners would be able to keep their homes at current values for a three year period even if they extend or refurbish.
The measure would also protect against any rise in property prices increasing the tax.
It is also likely that exemptions to the tax will be similar to those which exist for the household charge.
That would mean people who live in ghost estates and those who receive state support to pay mortgages won't be liable to the tax.
