The Revenue Commissioners has extended the deadline for filing Local Property Tax returns until 8pm tomorrow evening.
The deadline had initially been set for midnight tonight,.
A spokesperson for Revenue said it had taken the step to extend it due to the unprecedented volume of phone calls today.
The spokesperson said there are now 10,000 people filing over the phone and online every hour.
Earlier Revenue reported a surge of quarter of a million people filing Local Property Tax returns since yesterday morning.
It had received 1.44m returns by 5pm this evening, indicating a compliance rate of over 80%.
Revenue sent 1.66m notifications to liable property owners and had hoped to achieve compliance of 80% or above by the end of the year.
Over 22,000 people contacted the helpline yesterday.
Socialist Party TD Joe Higgins this morning said that he wants to harness "people power" to force the abolition of the tax.
Speaking on RTÉ's Morning Ireland, he said opponents of the tax would continue to boycott it.
The Revenue Commissioners' Local Property Tax helpline, 1890-200-255.
