The collatio lustralis was a tax on "traders in the widest sense" in the Roman Empire. It was instituted by Constantine, although there are some indications that such a tax existed during the reign of Caligula. It applied to both the Western and Eastern Empire, It was originally collected in both gold and silver, but only in gold beginning in the late 4th century. Like many Roman taxes, it was collected not annually, but every four years. It applied to all merchants, money-lenders, craftsmen, and others who received fees for their work, including prostitutes. The only initial exemptions were physicians, teachers, and farmers selling their own produce. Wikipedia [ - ]

The collatio lustralis was a tax on "traders in the widest sense" in the Roman Empire. It was... [ + ]