Revenue is to compare the property tax bills paid by neighbours to catch householders who undervalued their homes.
The taxman is giving homeowners a final warning to pay their property tax and household charge in the next six weeks.
From April 1, the taxman will be chasing the 100,000 homeowners who have not paid up their property tax for 2013 and the 460,000 who haven't paid the household charge for 2012.
Donegal has the lowest level of compliance with payment of the local property tax.
New figures from the Revenue Commissioners confirm the gulf in property tax bills between urban and rural areas – with homeowners in Dublin paying around 80pc more property tax than people in the rest of the country.
Although the bills reflect the higher property values in the capital, the figures will prompt further debate about the equity of the system, where the tax bill is based on where you live rather than the size or standard of the house.
Revenue is targeting its warning to four types of homeowners who have:
* Not paid their 2012 household charge.
* Not filed and paid their 2013 and 2014 local property tax.
* Undervalued their property.
* Claimed an exemption they were not entitled to.
These homeowners have until March 31 to bring the property tax up to date and avoid interest and penalties. Failing to avail of this opportunity will result in interest being charged, mandatory deduction from wages or a tax clearance certificate being held back.
Prosecution in the courts is also possible. Revenue can also refer the case to the sheriff.
Revenue is specifically warning people who undervalued their property to correct the value and pay the higher rate of tax.
Property Tax project manager Vivienne Dempsey advised homeowners to avail of the six-week window "to regularise your position".
Ms Dempsey said the tax authorities will be identifying what she called "outliers" – homeowners who have clearly undervalued their houses.
"We will be using statistical analysis to compare property values across areas. We have some pretty sophisticated analysis," she said.
Revenue's software highlights houses which are obviously valued lower than others in the street, estate or area.
Houses valued at €100,000 less than similar houses in the neighbourhood pop up on the radar.
Revenue's database lists all houses by address and gives the general size and number of bedrooms in a particular area.
Already, 1,400 homeowners have corrected the valuation since last November.
Homeowners who are caught undervaluing their houses will have to pay the higher tax and interest and penalties.
The taxman is also warning that failure to self-correct an understated valuation will lead to difficulties in selling the property.
Donegal has the lowest level of compliance with payment of the local property tax, with 87.1pc of property owners paying for 2013.
South Dublin has the highest level of compliance, where 94.7pc have paid up.
Figures released by Revenue show 1.810 million homeowners have paid up for 2013 – an overall compliance rate of 93pc.
Revenue's latest statistics indicate the national average property tax bill this year will be €267, suggesting an average house value of €148,000.
But the average property tax bill in Dublin is €394, indicating an average property value of €218,000.
Outside of Dublin, the average property tax bill is €218, reflecting an estimated home value in the rest of the country of €121,000.
The lowest average property tax bill is in Longford at €135, which suggests an average house value of €75,000.
But the highest average property tax bill in the country is in Dun Laoghaire-Rathdown where homeowners pay €646 – almost five times as much as in Longford.
The suggested average property value in Dun Laoghaire of €358,000 reflects the county council area having some of Dublin's wealthiest areas, including Dalkey, Killiney, Foxrock and Blackrock.
From April 1, Revenue is warning interest and penalties will kick in. Homeowners who haven't paid the household charge already owe €200 and this will rise to €213 in six weeks' time and continue upwards.
Mandatory deduction from wages and occupational pensions of unpaid household charge, including interest, will start in April for those who have not paid the €200 liability.
Unpaid property tax bills will rise by 0.2pc per day from the date the tax was due.
Finance Minister Michael Noonan last night backed Revenue's clampdown.
"The Revenue want to make sure that everybody who has a property which is liable for property tax actually pays,'' he said.
"It's not fair to those who pay if there's even a small group of people who don't pay. They're going to go after the small group who haven't paid.
"There's some people not liable. We're not talking about people who don't have a liability.
"We're talking about a small tranche of non-compliant taxpayers on property tax and I think the suggestion is there'll be a six-week window in which people can report to Revenue and pay their tax," he added.
Revenue is advising anyone who needs to put their affairs in order to go through the local property tax system on revenue.ie or call the helpline on 1890 200 255.
Fionnan Sheahan and Paul Melia