Dublin Bus confirmed yesterday that almost €1 million worth of 'change' or 'refund' tickets remain unclaimed.
The figure marks a decline in the amount sitting idle in the coffers of the capital's bus providers since last year.
Tickets issued in lieu of cash are given to passengers who do not have the correct fare when beginning their journey.
Ms Gráinne Macken, spokeswoman for Dublin Bus, said: "At present there is between €800,000 and €1 million left unclaimed.
"The money will remain in the system and it can be reclaimed at any stage. There is no time limit on when the change can be refunded and while we want to offer our customers the best service possible, we have found the system to be quite arduous logistically."
The uptake of pre-paid tickets - almost half of all passengers use pre-paid tickets - as well as the rounding off of fares has significantly reduced the number of change tickets being issued, according to Dublin Bus.
The abolition of the change facility on Dublin's 1,100 buses came in the wake of a series of physical attacks on drivers.
The Government has been urged to take control of the surplus funds.
Fianna Fáil TD Charlie O'Connor, a long standing campaigner on the issue, said: "I've raised this issue on a number of occasions and I feel strongly that the money should not just disappear into a black hole but should be put to some good use.
" I think that the money could be put toward greater access for the disabled and the handicapped. It is time that something is done with that money and I think the public would agree."
Mr Roderick Smyth, a Tallaght-based councillor and member of the Dublin Bus Forum, said: "It's ridiculous to suggest that Dublin Bus are not earning interest on the money.
"It's hardly been kept under a mattress or in a corner. The money should be either donated to charity or used to improve the service to those suffering from disabilities."
Dublin Bus said it was powerless to use or move any money not belonging to it.
Numerous Dublin-based charities, including Trócaire and Jack and Jill Children's Foundation, have run campaigns asking passengers to donate their surplus tickets.
Members of the catering staff in Trinity College Dublin have an ongoing campaign for the collection of change tickets.
The monies collected are donated to charities involved with the homeless in the city.