The House and Senate joint sitting has been set for Wednesday to vote on the new prime minister after their speakers and deputies have been endorsed by His Majesty the King.
House speaker Chuan Leekpai said on Friday that he had consulted Senate speaker Pornpetch Wichitcholchai and both agreed on the joint meeting of the two houses on Wednesday.
The meeting will be held at the auditorium of TOT Plc.
As the House speaker serving as Parliament president, Mr Chuan will chair the joint meeting.
The new prime minister needs a majority vote from the two houses, or 376 of 750 votes. The 250 senators were handpicked by the National Council for Peace and Order, led by Prime Minister Prayut Chan-o-cha.
Gen Prayut is expected to sail through the vote, provided all or most of the 250 senators vote for him, since the Palang Pracharath Party (PPRP) and its allies already command 198 votes. Forming a government is another story since senators are not allowed to jointly vote on most issues such as budget approval and no-confidence debates.
The Palang Pracharath Party (PPRP) and its bloc will nominate Gen Prayut to be the government leader. The anti-regime camp has not revealed its choice.
The Royal Gazette published the king's endorsement of the House and Senate speakers, as well as their deputies, on Friday.
Mr Chuan of the Democrat Party will be helped by first deputy Suchart Tancharoen of PPRP and second aide Supachai Phosu of the Bhumjaithai Party.
The upper house has named Gen Singsuk Singphai as the first deputy speaker and Supachai Somcharoen as the second.
They received the royal command before the portrait of the king in a ceremony held at Parliament.