REVENUE may have to chase up to 250,000 homeowners who do not register for the local property tax (LPT) by midnight tonight, a top official has admitted.
Today is the deadline for filing LPT returns online, with property tax letters and forms having been issued to more than 1.6 million property owners.
Revenue's LPT tax manager Vivienne Dempsey said they estimate a compliance rate of about 80pc.
The tax authority is expecting a last-minute rush by householders to register today.
That would leave 200,000 to 250,000 who will not have filed returns by tonight's deadline, Ms Dempsey said.
Some €22m had been collected in payments under the LPT by the end of April.
People could opt to make phased payments until the end of the year at no extra charge, but under self-assessment there was a statutory obligation for liable persons to file returns.
Non-payment was not an option and those who fail to file on time will be penalised.
Reminder letters will be issued warning of the powers to deduct from source those who fail to pay.
Revenue will be writing in early June to those who failed to register.
The tax authority will be writing to employers to deduct the tax from pay in July.
Next in line will be people receiving occupational pensions, followed by those receiving certain government payments such as social welfare.
The self-employed will be hit once they file annual returns in October and a surcharge could be applied.
Ms Dempsey said there was "an inevitability" about the tax as a property could not be sold or transferred until LPT had been paid.
Homeowners can file online until midnight tonight by logging on to www.revenue.ie using the property ID and PIN and following the instructions or by ringing 1890 200 255.
In the case of homeowners who have not received a return, they are still liable for the tax and must file a return online or over the phone.
The Campaign Against Home And Water Taxes said there was nothing inevitable about paying the property tax.
"People can and will choose to take part in a boycott as a way of exerting political pressure on the Government," spokeswoman Ruth Coppinger said.
"Hundreds of thousands are likely to take part in an organised boycott of this unjust bondholder tax.
"Many have simply decided they have no more to give."