Revenue officials were forced to close its busiest public office when protesters picketed against the controversial household charge.
One man locked himself to a radiator inside the Central Revenue Information Office on O'Connell Street in Dublin while another 20 demonstrated outside.
Revenue said staff had to close the busy office, which deals with more than 1,000 callers each day, due to the occupation of the office by protesters.
"As our main priority is the health and safety of our staff and customers, we had to close the office," a spokeswoman said.
"We regret the significant inconvenience this has caused our customers."
A Garda spokeswoman said the protest ended peacefully shorty before 3pm on Thursday.
"There were no injuries and no arrests," she added.
The deadline for local property tax returns is next Tuesday.