The Taoiseach Enda Kenny is warning that the Revenue Commissioners will pursue any home owners that do not pay the Property Tax.
The deadline for filing a return online has been extended until 8pm this evening, after which penalties will apply for late registrations.
More than 1.6 million properties are liable for the tax, and so far Revenue have said that in excess of 1.5 million households have registered.
Mr Kenny said Revenue has the full backing of the Government to ensure people who do not contribute will do so.
He said: "I understand that over 1.5 million people have registered.
"Clearly the Revenue Commissioners have the authority, the power and the backing of Government to see that those who don't contribute, will do so."