Finance Minister Michael Noonan has said people who invest in their homes by adding extensions may have to pay extra property tax.
The new tax which comes into effect later this year will be self-assessed, but based on the value of the property.
Responding to questions in the Dáil, the Finance Minister said if an owner increases the value of his or her property by building on, they will be liable for extra tax.
"If you have an extension built and all your neighbours are saying 'My house is between €150,000 and €200,000, but you put another €75,000 (or so) onto it by way of extension, then the normal thing is you go up to the next band, and the tax will apply (at the higher rate)," he said.