The Residential Tenancies Board is applying a temporary pause on the charging of late fees in recognition of "the genuine difficulties" experienced by landlords who have been trying to register tenancies.
It is also in the process of refunding landlords who were charged late fees between August and November last year, with over 80% of late fees imposed during that time refunded to date.
The RTB did not confirm the exact number of landlords who were charged late fees, nor did they say how many complaints they have received relating to late fees.
A spokesperson said, "The number of complaints related to late fees will be collated and published in the RTB's 2022 Annual Report and Accounts".
The temporary pause on the charging of late fees applies to new tenancy registrations with a tenancy commencement date on or after November 12, 2022, and for annual registrations of existing tenancies which became due on or after November 12, 2022.
The RTB introduced a new tenancy management system in November 2021 in preparation for the introduction of annual registration which took effect on April 4, 2022.
Landlords must now pay €90 to register a tenancy every year. Previously, landlords had to pay €90 to register a new tenancy, or €90 every 4 years to re-register an ongoing tenancy.
An additional fee of €90 is charged to landlords who are late registering a tenancy.
However, many landlords who tried to register a tenancy online following the introduction of the new system last year were told that the RTB could not verify their accounts.
During the summer, the RTB shut down its web chat service and moved staff to answer the "high volume of calls" that it was receiving from landlords and letting agents.
It apologised for the delays in responding to its customers at the time.
In September, it posted on its website: "The RTB's online tenancy registration system is experiencing difficulties in relation to account creation. We are investigating these issues and will update customers when further information is available. We apologise for any inconvenience caused."
In response to a query from RTÉ News, a spokesperson for the RTB said the annual registration process has been "bedding in for several months" while the public body "closely monitors the system's performance and stability".
"The RTB is fully aware that some of our customers have and continue to experience issues with our new tenancy management system, and we would like to sincerely apologise for any inconvenience caused to date."
The spokesperson said the RTB is committed to working collaboratively and constructively with landlords and letting agents who are using the new registration system to complete their annual registration in 2022.
They said they are making all efforts to ensure that subsequent cycles of annual registration run smoothly for landlords and letting agents.