A ruler must calculate the total amount of salaries for officials and administration expenditure of all levels of government, and on this basis, determine the amount of tax to be levied on the people.

(Records of the Historian)

The government may collect a tax of one tenth of a liang of silver for the expropriated labor of a hundred people. The total amount of tax to be collected should first be calculated, and on this basis, taxes levied on the people. This is called spend-and-tax.

(The Old Tang History)