Zoyo (雑徭)
The zoyo tax system was one in which taxes were paid in the form of labor, under the Ritsuryo system (a system of centralized government based on the ritsuryo code) in China and Japan.
Zoyo in Japan
The zoyo in Japan was based on the Chinese system, but it was introduced after being modified to meet the conditions of Japan.
The kokushi (provincial governors) in local areas impressed and organized people so as to compel them to develop an infrastructure (such as flood control work and irrigation construction) and to renovate buildings such as the kokuga (provincial government offices). The first zoyo is believed to have been established in the "Asuka-kiyomihara-ryo" code of 692. Initially, the maximum number of days per annum for the zoyo was less than or equal to 60 for the seitei (a male between the ages of 21 and 60), 30 for the jitei (a seitei with disabilities) and the rotei (a male over age 60), and 15 days for the chunan (a male between the ages of 17 and 20), but the Kyakushiki code (a code to amend and supplement the Ritsuryo code) intended to reduce the zoyo by half was introduced in 757. The maximum number of days was restored to the original amount after the death of FUJIWARA no Nakamaro, but in 796 it was reduced by half.
It was the kokushi's right to impose the zoyo, and among the kokushi there was some who imposed the zoyo for personal use; it is commonly accepted that the zoyo became a burden to the komin (the registered people, especially farmers, under the Ritsuryo system) and thus caused the handen farmers (farmers whom the government had given the handen, or the allotted land for farming) to decline, abandon the land and flee to other domains.
Zoyo (or zatsuyo) in China
The zatsuyo in China was established in the Northern Wei dynasty and was completed during the Tang dynasty. In the Tang Dynasty, the local governments impressed people. Many details remain to be clarified, and there are two theories about the zatsuyo (zoyo): one is that the zatsuyo as well as the soyocho (a tax system under the kinden system, or the equal-field system) was a basic tax; the other maintains that the labor to the government was basically provided in the form of the saka (labor allocated by rank, 差科), a major example of which was the shokueki (職役), or the transport of goods), being a different tax system from the soyocho. However, in Japan the saka system, in which the ko (an administrative unit of a few families under the Ritsuryo system) was classified by rank and the labor was allocated according to rank, was not adopted and therefore the zoyo, free of rank, was mandated. Additionally, there is a controversy regarding the burden of labor, in which one theory indicates that the burden was always mandatory and the other claims that it was a provisional tax that wasn't uniformly imposed. The yo was a part of the soyocho from which it was possible to be exempted; this annual mandatory 20 days of labor could be substituted with 40 days of the zatsuyo. The zatsuyo was effectively a substitute tax for the yo.