The primary source of direct tax revenue was individuals, who paid a poll tax and a tax on their land, construed as a tax on its produce or productive capacity. Supplemental forms could be filed by those eligible for certain exemptions; for example, Egyptian farmers could register fields as fallow and tax-exempt depending on flood patterns of the Nile. Tax obligations were determined by the census, which required each head of household to appear before the presiding official and provide a head count of his household, as well as an accounting of property he owned that was suitable for agriculture or habitation.