XII.1.11
Emperors Gratian, Valentinian, and Theodosius Augusti to Hesperius, Praetorian Prefect.
Although the payment of the lustral tax payable in gold has in view all merchants, nevertheless, clerics withing Illyricum and Italy shall have the right to follow the occupation of tradesmen exempt from taxation to the extent of ten solidi each; within Gaul, to the extent of fifteen solidi each. If any capital is exmployed in business, beyond this amount, however, it must be subject to the payment of this tax payable in gold.
Given on the third day before the nones of July at Aquileia in the year of the consulship of Auxonius and Olybrius. July 5, 379.
(trans. Pharr 1952: 386)