Irish Rail says the penalties were for different types of fare evasion.
Rail bosses say that since January 2018, 19,908 people were caught out on board without a valid ticket for their journey.
20% were fined for not using their Leap Card to tag on prior to travel, while 13% were adults who were penalised for travelling on a child or student tickets
Some fines were issued to people without any ticket at all.
Luas Operator Transdev has said that it is satisfied that 9 out of every ten of its passengers pay the correct fare, while the Social Democrat Catherine Murphy managed to obtain figures from Dublin Bus that show that is had collected 25,000 euro from 500 fines since the start of 2017.
Iris Rail says some 6,000 penalised passengers appealed their fine- 741 were successful.