Every adult in a car travelling across the border from Northern Ireland without a valid reason will be fined 100 euro.
New regulations came into force this morning with on-the-spot fines for breaches of travel restrictions to all visitors to the state.
People given a Covid-19 related fine have 28 days to pay.
Damien McGinnity from Border Communities Against Brexit says the new regime is a direct result of the politicians in Belfast and Dublin failing to work together.
He says a lack of political leadership on both sides of the border is to blame.
