To determine the amount of taxes they would pay. The census in Roman times was an income assessment for taxation purposes. Not all men were required to do the registration. It was the prates families (fathers of the family) who did this. These were oldest male in the family and were the heads of the household. They had to declare the assets of the household, how many family members there were and who they were because these assets belonged to him and because he had authority over the whole family.The other members of the household were not required attend the registration. This made the job of the officials who carried out the census easier and reduced the amount of inconvenience on the citizens. Since the slaves of a household were owned by the household, declaring how many slaves a household had was part of the declaration of the assets of the household. Only rich households could.
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