The fusion of the field tax with the poll tax (diding heyi 地丁合一, also called tanding rumu 攤丁入畝 or tanding rudi 攤丁入地 "to apportion the poll tax to the field tax" or ding sui di qi 丁隨地起 "the poll tax geared to the field tax") was a tax reform of the early Qing period 清 (1644-1911). It made taxation easier by allowing to pay both levies in money, and not the one in money or corvée service, the other in kind. The imperial decree from 1712 regulated, based on the census of the year before, that the registered population—with a size of 24,621,324 persons, deliverd a poll tax (dingyin 丁銀, short ding 丁) quota of 359,000 tael. Any increase in the population size would "in eternity" never entail tax increases (zisheng renkou, yong bu jia fu 滋生人口，永不加賦). The reform was first tested in 1716 in Guangdong, and then in Sichuan, but in both places landowners resisted. In 1723, when the Yongzheng Emperor 雍正 (r. 1722-1735) came to the throne, he extended the regulation to the whole country. The system started by and by in 1724, but the last provinces to adopt it were Guizhou in 1777, and Jilin and Fengtian 奉天 (approx. today's Liaoning) in the late nineteenth century.
The principle for the assessment of taxes was the height of the field tax (tianfu yin 田賦銀, short di 地). The higher the latter, the higher was the poll tax. The creators of the tax reform used existing figures about the height of the poll tax in each district and leveled it regionally. It was then added to the field tax as a certain quota of the latter. For historical reasons the height of the field tax differed everywhere, and so did the poll tax. The lowest proportion was 0.001 tael/liang per tael of field tax, and the highest one 0.5 tael. In the province of Zhili, for instance, it was 0.27 tael per tael of field tax, but in Henan it ranged from 0.11 to 0.27 tael per tael of field tax. The poll tax was higher in regions with a larger population.
Landless peasants were exempted from the poll tax, which meant a substantial reduction of their tax burden by the reform. Because it had been as high as 4 tael in some regions, many peasants had tried to evade the poll tax, so that officials used to say that the poll tax quota was not easy to establish, due to the difficulties of levying it. Owners of large estates, members of the local gentry, were often able to avoid taxation, so that there was the saying that the rich landowners did barely pay taxes or deliver corvée labour, while the tenant farmers were fleeced and exploited. The reform from 1724 allowed the government a better control over revenues to be expected, and diminished the tax evasion by both poor peasants and the landowning gentry.