The Government has granted Mr Justice Nial Fennelly a further three months to complete his investigation into the recording of telephone calls in and out of Garda stations.
Mr Fennelly has been granted permission to continue his work until March 31st.
When established by the Department of the Taoiseach in April 2014, the commission was asked to finish its work by the end of that year. However, it has now been granted additional time on three occasions, originally to the end of September of this year and then to December 31st.
The judge released an interim report which examined issues around the departure of former Garda commissioner Martin Callinan.
It is now looking at the wider issue of covert recording of calls, including between people in custody and their solicitors, in the Garda Communications Centre in Dublin and at each of the 23 divisional headquarters outside Dublin. The time period being examined stretched from January 1st, 1980, to November 27th, 2013.
Part of the retired Supreme Court judge’s work includes examining if the taping of calls had implications for the Garda investigation into the death of French film-maker Sophie Toscan Du Plantier in Co Cork in December 1996.
The Department of Public Expenditure has previously declined to give details of legal costs or other expenses paid to the judge or his staff. It said the terms and conditions were agreed and sanctioned by the department.