Fares will increase for cross-Border rail journeys on the Dublin-Belfast Enterprise service from next Monday, April 2nd.
Iarnrod Eireann has said the increase is due to "inflation and currency differentials".
Fares will increase on both sides of the Border, but will not affect services between Dublin and Dundalk.
A single Dublin-Belfast ticket - and also a day-return ticket - will cost £21, up from £19. A monthly return Dublin-Belfast ticket will cost £32, up from £29, while a First Plus monthly return will cost £55, up from £50.