Dead people will be sent payment demands for the local property tax over the coming weeks, the taxman has admitted.
Revenue said it was inevitable mistakes would be made collecting the controversial levy, including letters being issued to deceased persons where a house or flat was not legally transferred to new occupants.
Josephine Feehily, chairman of the tax and customs agency, said people in the countryside particularly often lived in homes that are still registered in the name of their dead ancestors. She said: "We are fairly sure we will unfortunately send out letters in error to some people who are deceased, because property transfers have not been completed. That isn't unusual in rural Ireland."
Ms Feehily said because there was never an official property register in the country, it was impossible to tell if a house had been passed down through generations without being legally handed over.
"I hope it will happen in a very, very tiny number of cases," she said. "But it would be foolish of us not to alert people to the fact that if a property is still in the name of your grandparents or great-grandparents - and I do know cases where that happens - it would be foolish of us not to acknowledge that that exists in the Irish culture and to alert people to the fact that it might happen."
The country's chief tax collector said she was not trying to "frighten" people but wanted to warn the public that such errors were likely. Other cases where mistakes are likely include when a landlord has not registered with the taxman and a tenant is thought by Revenue to be the property owner.
Ms Feehily appealed to any tenants receiving demands for the local property tax in the coming weeks to "quickly" contact Revenue and let them know. Otherwise, they could be held liable for the payment. Where someone has paid the household charge on behalf of a householder - for example a son or daughter making a payment for their parents - they may also be wrongly assumed to be the property owner. "The message is, if you are not the owner, tell us," said Ms Feehily.
People will have 30 days to contact Revenue to prevent the processing of a further demand for payment. Letters for the self-assessed tax will be issued to 1.66 million householders from next week. It is likely the process will take four weeks to reach all homes.
Owners must decide themselves what the market value of the property is as of May 1. An online guide is expected to be available from Sunday on www.revenue.ie which will give average values for different property types in each of the 3,400 electoral districts across the country.
The Campaign Against Home and Water Taxes said it was organising a nationwide boycott of the levy, including country-wide meetings, public pickets and protests. A "major national demonstration" is being planned for Dublin on April 13.