"The inclusive national dialogue will be convened from August 20," the junta-appointed prime minister, Albert Pahimi Padacke, said in a decree issued Thursday.
The impoverished Sahel state was buffeted in April 2021 when its veteran president, Idriss Deby Itno, died fighting rebels.
His son, Lieutenant-General Mahamat Idriss Deby Itno, immediately took over at the head of a junta.
He dismissed the government, dissolved the parliament and repealed the constitution, vowing to hold "free and transparent" elections in 18 months -- a deadline that he said could be postponed once if "certain conditions" were not fulfilled.
In August, Deby announced plans for holding a national dialogue that would set the stage for holding presidential and parliamentary elections.
But the forum has been repeatedly postponed in the face of discord among armed rebel groups and rejection by Chad's political opposition, Wakit Tamma.
The gathering was initially set for February 15 and then delayed to May 10.