Revenue is warning that those who seriously under-declared their Local Property Tax return will be getting letters from April. Chairwoman Josephine Feehily says they have already tackled some for lowering the value of their home and got money off them.
Meanwhile it has been revealed at the Public Accounts Committee (PAC) that several hundred thousand - maybe close to 500,000 - never paid the household charge.
There is a compliance rate of 93% on the property tax for 2013 and 1,000 people a day are still paying it. But Revenue is now going after the predecessor - the houshold charge - and those who did not pay it.
The two datasbases suggest 460,000 never paid the household charge though Josephine Feehily admits that may be overstated because of the difference in databases.
Revenue is also now focusing on those who under-declared the value of their homes and what your neighbour did will have an impact.
She says they have already challenged a handful of people on the issue, got money off them - and lots of letters will be landing from April.
And if you think you have under-declared and want to admit it, you can change it online until the end of March with no interest or penalties.
Earlier this week, the Revenue Commissioners extended the property tax deadline until March 31st is before a nationwide compliance programme is launched.