One motorist has refused to pay over €155,000 in owed M50 toll fees.
The driver travelled the road 1,018 times in 2014 but never paid his owed toll fees.
The Irish Independent reports that over €100m was collected in fees from over 43m journeys on the road, although over €5m in fees went unpaid as hundreds of motorists failed to pay.
The M50 operates a barrier free toll system which has largely met with compliance from motorists paying tolls owed.
The non-payment - 4 per cent of drivers - was a 25 per cent increase on 2014.
More than one third of unpaid fees were owed by cars with international registration plates, with 95 per cent of them from the UK.
The National Roads Authority has said they can chase debts by issuing legal proceedings and have hired a London-based debt collection agnecy.
