REVENUE boss Josephine Feehily has warned that it will be very difficult to avoid paying the new property tax.
She said the authorities have extensive powers to collect the levy and will use them against people who "do not engage with us".
But the chairman of the Revenue Commissioners also admitted that thousands of people will receive property tax demands in error.
Ms Feehily said letters about the new tax may end up going to the wrong people because the authorities have the wrong name for the owner or a family member paid the household charge.
The owner may have died, but the formal transfer of ownership may not have taken place. Tenants may also get the letter by mistake. The onus is on anyone who gets a letter in error to tell Revenue, said Ms Feehily.
"Because there is no existing property register, there will be errors in some cases. We are conscious people will get a letter in error," she said, launching a new information campaign.
Homeowners are due to start getting letters from next week, outlining how the tax works, including a rough estimate of their property's value, and including a two-page form that has to be filled out.
There will also be details on how to assess your property to check if the estimate is correct, and details of how to pay. The form is due back in May, with payment in July for half of the year.
Ms Feehily said the new tax was a self-assessed charge and it was up to homeowners to research their home's value and tell Revenue what it is worth.
"We are not valuing individual properties. We don't know what your house is worth, what condition it is in, and how big it is. We know you have a house, that's all," she said.
People who refuse to fill out the two-page form will have to pay the estimate Revenue has placed on the property.
The tax authorities are presuming that people will be honest about what their homes are worth. Valuations do not need to be too exact.
Revenue will launch an online valuation tool on its website on Sunday. This will allow people to enter some details about their house and pinpoint their location on a map, and they will be given an indicative value.
"We have made this one as easy as possible to file and as easy as possible to pay, but it will also be difficult to avoid," Ms Feehily said.
"We will use the Revenue estimate for the tax due on the property if people do not engage with us, and we will be pursuing it."
The tax body expects at least 80pc of homeowners to have paid the tax at the end of the first year.
Anyone who refuses to pay will have the money taken from their salary, pension or social welfare payments.
Meanwhile, Tanaiste Eamon Gilmore has defended the introduction of the property tax, saying householders will be able to engage with Revenue if they feel the estimate of the value of their property is wrong.
Mr Gilmore was responding to questions from Sinn Fein's Mary Lou McDonald in the Dail.
Ms McDonald said the Government was planning to put its hand into the pockets of people who were struggling, with a tax that took no account of individual circumstances.