συμμορίαι, symmoriai) was a group of wealthy citizens in Classical Athens during the 4th century BC, assessed together for the purposes of taxation.
[3] Due to the inevitable delays in collecting taxes from so many people, shortly after 360s BC, the proeisphora was introduced, whereby the three richest members–the hegemon (ἠγεμῶν, "leader") or protos (πρῶτος, "first"), after whom each symmoria was named, and the deuteros (δεύτερος, "second") and tritos (τρίτος, "third")—of each symmoria paid in advance the sum due from the rest.
Each was headed by a treasurer (tamias, ταμίας), and the tax officials, likewise drawn from the metics, were termed epigrapheis (ἐπιγραφεῖς).
[8][9] By the middle of the 4th century, however, the trierarchic system had become dysfunctional, not least due to the growing unwillingness of the wealthy classes to contribute time and money to the task.
[1] In the 330s or 320s BC, one of the ten strategoi of Athens was given charge of the symmoriai system, and was termed strategos epi tas symmorias.