The Revenue Commissioners are to give individuals who have not paid the property tax or household charge until the end of March to comply with the levies.
The tax authority said there is now a six-week window for people to pay the outstanding amounts 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.
Revenue says it will begin its compliance campaign from the beginning of April.
People who have not complied by 31 March will have interest back dated to 1 July 2013. It will charge tax of 8% per annum.
"Penalties will apply to those who seriously do not comply with us," said the Revenue's project manager Vivienne Dempsey.
She added that 460,000 properties had not paid the household charge. Some of these may be entitled to an exemption.
However, 242,000 properties have workers in the properties who will now be subject to mandatory deductions from their pay at source.
If you have not yet paid your LPT, you can contact Revenue at 1890 200 255 to arrange to do so. If you undervalued your property, you can self-correct this valuation and pay the additional liability by March 31st by using its online service.