Under the guidelines, houses that are worth less than €100,000 will only have to pay €90 of property tax.
It emerged earlier that the number of households exempt from the tax is dramatically lower than those exempt from the €100 household charge, and stands at 5,000 homes.
Housing Minister Jan O'Sullivan said that if a house is genuinely "worthless", the owner will only have to pay €90 tax on it.
"If you're close to zero, then you're in the €90 a year bracket, which is the same as a Local Authority house," she said.
"All the Local Authority houses are going to be in the lowest assessment category.
"If you believe your house is worth less than €100,000 well then you put yourself into the lowest category, and you do it legitimately."