All posters relating to the abortion referendum must be taken down by midnight on Friday.
Section 19 of the Litter Pollution Act 1997 and the Electoral (Amendment) (No 2) state that referendum posters must be removed within seven days of the polling date.
After that, the posters will be classed as litter and those responsible for erecting the posters will be subject to a fine of €150.
"Where posters remain in place we will arrange for their removal and seek to issue fines to those responsible," said Dublin City Council.
South Dublin County Council said all unmarked referendum posters must be reported to An Garda Síochána.
Section 140 of the Electoral Act 1992 requires every poster to be marked with the name and address of the printer and of the publisher.
The omission of these requirements is an offence punishable of a fine up to €634.87.
“Local Authorities are not responsible for enforcing this aspect of the Electoral Act,” said the council.
An Garda said that any reports made would be investigated locally.
The responsibility for enforcement of the litter law lies with the individual county councils.
A representative from LoveBoth said: "Our volunteers are working hard all around Ireland to have all our posters down by tonight in accordance with our obligations."
Together for Yes said: “We hired a company to take down the posters and our goal is to have them all down by the deadline.”
Referendum posters can be recycled free of charge at South Dublin County Council Civic Amenity in Ballymount until June 8th or in Dublin City Amenities until June 9th. Most other councils will provide similar facilities.
