Som Sa-at (Thai: สมสะอาด) is a tambon (subdistrict) located in the mid-west region of Det Udom District, in Ubon Ratchathani Province, Thailand.

[3] Before 1997, Som Sa-ad tambon was governed by its subdistrict council, but such a local government has been promoted to the Subdistrict Administrative Organization of Som Sa-at (องค์การบริหารส่วนตำบลสมสะอาด; Som Sa-at SAO) in February 1997, the first subdistrict member court election happened in May that year.

[1] In 1966, together with the area divided from Na Suang and Thung Thoeng, the northern region of the tambon was split to form a new subdistrict, Na Charoen.

[3] Som Sa-at subdistrict is divided into 12 administrative villages (mubans; หมู่บ้าน), one of which, Muang village, was further divided into two community groups (Mu; หมู่).

[2] The following is a list of the subdistrict's mubans, which roughly correspond to the villages, as of the 2021 census.