Over the course of several months, RTÉ Investigates reviewed expense records from every local authority in the country, as well as records from numerous other public bodies that pay councillors' expenses.
Through freedom of information, RTÉ Investigates obtained details of expense claims from every local authority in the country.
This information was then cross-referenced with data obtained from over 30 public bodies, which also pay councillors expenses.
The records reveal that hundreds of councillors contravened the Local Government Act by failing to declare expenses they received from external organisations.
Many councillors across the country have received double payments, by wrongly claiming expenses from their own local authority and from an external organisation for the same official absence.
For example, there was one tale about former Sligo County Councillor Jerry Lundy, who claimed expenses to travel to conferences and training events in Ireland - which coincided with Committee of the Regions events he attended, in places such as Brussels and Spain.
And it's safe to say that the revelations left viewers absolutely fuming.
"Jawdropping. Outrageous behaviour by some councillors" said one man with another user agreeing, asking: "Wonder how many councillors will lose their positions after this tonight."
Another noted "Mr Lundy can be in two places at the one time.... Amazing man...."
While a fourth joked "I think by the end of #RTEInvestigates I may have to go into Counciling ..for the .money"
Another said: "Shameful abuse of taxpayers money. Those councillors abusing the expenses system should be named and shamed and made repay with interest any expenses falsely claimed"
You can catch up on the Prime Time episode on the RTE Player.
