Joden (定田) refers to rice fields which were designated, as a result of a kenchu (land survey) on territories belonging to shoen (manors) and koryo (public lands), as taxable lands in regard to the payment of kanmotsu (tribute goods paid as taxes or tithes), shoto (tax on rice fields), nengu (annual tribute, land tax), and kuji (public duties). They were regarded as the benchmark for taxation imposed within shoen and koryo. They were also called jokojiden or jokoden. Of the rice fields within shoen and koryo, there were two categories of fields; joden (定田, taxable rice fields) and the rest, which were categorized as joden (除田, tax-free rice field). The dimensions of the tax-free rice fields, however, could change as a result of an emergency kenchu in a time of disaster, and the dimensions of joden changed accordingly.
In the manors, myoden (rice-field lots held by a nominal holder), which were subject to nengu and kuji, were generally categorized as joden, but also any lands which were subject to zoyakumen (exception from all levies except the regular land tax) including the cultivation of fields and rice fields directly managed by the manor owners, as well as isshikiden (partially exempt fields), kyumyoden (rice fields given to an officer or a steward of a manor by his lord), and sanden (deteriorated rice fields) were included in the category. In later years cultivated fields were also regarded as joden.