The Green Party is urging the Government to introduce a capital gains tax on real estate.
Radio New Zealand last week revealed Treasury officials are working on such a move, although Finance Minister Bill English said the Government would take a lot of convincing.
Green Party co-leader Russel Norman says a capital gains tax on properties other than the family home has been a longstanding party policy.
Dr Norman fears another housing bubble might be building, and says the last boom was incredibly detrimental because it made housing so unaffordable, while misdirecting billions of dollars of investment, all of which was borrowed from overseas.
He says a capital gains tax is only one tool of a package which would include building more state housing.