Over 22,500 people contacted Revenue's Local Property Tax helpline today.
It has emerged that some homeowners have logged on to the system to find the online filing record stating their property has been filed and paid for, even though it has not.
Revenue says only a small number of people have been affected by this.
The problem has arisen in rural areas where homeowners have not been sent a property ID or PIN and where a number of houses may have the same postal address.
A spokesperson said the issue had been raised by a number of callers to the helpline today.
Revenue is advising these people to logon to the LPT website and select the “have not received a property PIN" option on the first page and complete the required fields.
When they are directed to the next page, they should select the address at the bottom and press 'continue'.
This uses the address they will have provided on the previous page, to generate a new entry for filing.
Home-owners can then file and pay as normal.
Meanwhile, Revenue says that, as of this evening, 1,265,000 property tax returns have been filed.
A spokesperson for the Revenue Commissioners says the helpline for homeowners who have yet to file their return is very busy and that staff have been dealing with a lot of callers through the day.
The helpline will be open on 1890 200 255 until midnight.