Although it was prescribed that Sabenkankyoku was responsible for Nakatsukasasho, Shikibusho, Jibusho, and Minbusho, and Ubenkankyoku was responsible for Hyobusho, Gyobusho, Okurasho, and Kunaisho, it is considered that Benkankyoku was as a whole responsible for the eight ministries in fact.
律令の規定では、八省のうち中務省・式部省・治部省・民部省を左弁官局が、兵部省・刑部省・大蔵省・宮内省を右弁官局が受け持つこととされていたが、実際には弁官局総体で八省を管轄したようである。