People living in Northern Ireland who cross the border without a reasonable excuse face a €100 fine from today. The new measures apply to anyone who is "not ordinarily resident" in the Republic of Ireland.
Gardaí said that if enforcement is required a fixed payment notice for €100 will be issued to each person who is in breach of the regulation.
If gardaí stop a car with a driver and two passengers then each of the three adults will receive a fine of €100. The new rules mean gardaí can turn back day trippers from Northern Ireland who cross the border.
Under the current Covid-19 public health restrictions, travel is restricted to within 5km of a person's home except for essential reasons.