Tax's immediate predecessor Elias Kwandikwa died in August.
The new Defense minister was the Executive Secretary of the Southern African Development Community (SADC).
In a mild cabinet shakeup, President Samia sacked Communication Minister Faustine Ndugulile, Miister of Transport, Leonard Chamuriho and Medard Kalemani, Minister of Energy.
January Makamba who was sacked by the late President John Magufuli has bounced back as Energy Minister.
Judge Eliezer Feleshi has been named as Tanzania's new Attorney General, replacing Adelardus Kilangi who has been offered an ambassadorial role.