Along with Shiki (ritsuryo system) and Ryo (ritsuryo system), Tsukasa was mainly placed under the ministries (Nakatsukasasho, Jibusho, Gyobusho, Hyobusho, Okurasho, and Kunaisho), Emonfu, and Kyoshiki to be in charge of clerical work.
職(律令制)や寮(律令制)と並び主に省（中務省・治部省・刑部省・兵部省・大蔵省・宮内省の各省）や衛門府・京職のもとに置かれて事務を行った。