Reminder letters urging those who have not paid the household charge to do so will begin arriving today.
Some 700,000 property owners have yet to pay the €100 household charge. Failure to pay the levy could lead to legal action, the Local Government Management Agency has warned.
A second letter will warn of the consequences of non-payment, while a third will threaten court action if payment is not made.
Jackie Maguire, chairwoman of the Household Charge Project Board, this morning said there was a "steady flow" of people paying.
Speaking on RTÉ radio, she noted many people left payments to the last minute, leading to a processing backlog after the March 31st deadline.
The Local Government Management Agency said it had analysed data to identify those who had not yet paid the charge. A spokeswoman said the Revenue Commissioners, ESB Networks, the Department of Social Protection, Private Residential Tenancies Board and other agencies had agreed to share data in order to identify non-compliant properties.
In a statement, the Campaign Against Household & Water Taxes said the reminder letters "will only add to the determination of the mass non-payment campaign".
"Deciding to send out thousands of letters threatening homeowners who have taken a principled stand in resisting the imposition of this austerity tax will not effect [sic] the peoples' determined resistance," said John Lyons of the campaign group.
There was widespread anger over the introduction of the charge. A protest march was organised on the second day of the Fine Gael ardfheis in March, with 5,000 people demonstrating outside the party gathering the day before the deadline for payment.