Members of the Public Accounts Committee will try to get to the bottom of where the Eircode system went wrong today.
Representatives from the Department of Communications will be asked to explain why the post code system is leaving some people confused despite a €38m investment to make it user friendly.
Every house in the country was given a seven-digit code last July that was supposed to make exact locations easier to find.
However emergency service operators have criticised the Eircode system.
PAC Chairman John McGuinness will lead the questioning in Leinster House today.
He said: "(The Eircode system) is a failure because it's not being used as widely as it should be.
"There are inaccuracies in it. State agencies don't use it and we need to understand why.
" We have to speak to those central to the project (and) correct the errors that were made to ensure it's more attractive to the commercial world and to those in government departments who would benefit from this."