Jishi Koeki (地子交易)
Jishi Koeki refers to the exchange (buying and selling) of rice as a land tax that was collected from koden (fields administered directly by a ruler) by a provincial governor under the Ritsuryo system (a system of centralized government based on the ritsuryo code); rice was exchanged for light commodities that were easier to carry and submit to the central government.
The origin of Jishi Koeki was found in an itsubun (fragments of a document) about a manager of tax officers under the Taiho Ritsuryo (Taiho Code) system. Governors of provinces that were required to submit a land tax quota would use rice collected from koden as a financial resource in order to purchase silk or iron based on koka (selling prices) and sent it to the Daijokan chuke (manager of the kitchen of the Great Council of State) in the central government. The tax was then used to pay the expenses of the Daijokan or provide for workers. Later on, Koden became territories of the Ozuki clan who took over the official position, and rice taxes from these territories, as well as commodities obtained through Jishi Koeki were spent as expenses for the Daijokan.