Leo Varadkar, currently the Tánaiste, will officially take office as Taoiseach on December 17.
The Fine Gael leader will take over from Micheál Martin on that date, a source told the PA news agency.
According to the Program for Government, the Taoiseach position rotation was supposed to take place on December 15th, but it is believed that this has been postponed to allow Mr. Martin to attend the last meeting of EU leaders in Brussels this year.
Previously, Mr. Varadkar held the position of Taoiseach from June 2017 to February 2020.