The Revenue Commissioners has said it will pursue hundreds of thousands of individuals who have yet to pay the Household Charge for 2011.
The €100 charge was introduced as an interim measure ahead of the Local Property Tax in 2013.
Revenue records suggest 460,000 householders who have subsequently paid the Local Property Tax have yet to pay the Household Charge.
Chair of the Revenue Commission Josephine Feehily told the Public Accounts Committee the final figure was expected to fall between 400,000 and 500,000 properties.
"We do know there are several hundred thousand who haven't paid (the Household Charge) and the matching would be right in 80-90% of cases.
"We'll be after them, that's really the message," she added.
Figures released by the Revenue show 58% of property owners self-assessed a different LPT valuation than the Revenue estimate.
44% returned a lower valuation band, while 14% returned a higher valuation band.
Ms Feehily said those who had undervalued their homes would be receiving letters from Revenue.
Asked what would happen if people were a few bands out compared to those around them, Ms Feehily said: "We have norms for areas and the further out people are from the norms, the more likely we are to begin with those."
She said a handful of cases had already been challenged.
Ms Feehily said people who sold their homes now for a higher price would not be affected.
"Good luck to them," she told the committee.
She said the May 2013 valuation date would hold until November 2016.
Revenue has given individuals who have not paid the Local Property Tax until the end of March to comply with the levy.
The tax authority said there is now a six-week window for people to pay the outstanding amount before interest and penalties will apply.
People who have undervalued their property or claimed an exemption which they are not entitled to also have to regularise their position by 31 March.
Overall compliance rates for the Local Property Tax in 2013 now stands at 93%.
In total, €315m was transferred by Revenue to the Exchequer in respect of the tax at the end of 2013.
South Dublin local authority area has the highest compliance rate at 94.7%, while Donegal has the lowest at 87.1%.