On August 17, the State Taxation Administration issued the "Notice of the State Taxation Administration on Clarifying the Implementation of Certain Individual Income Tax Policies", which clarifies the implementation of certain individual income tax policies. The first article of the "Reply of the State Taxation Administration on Certain Issues Concerning Individual Income Tax Policies" (Guoshuihan [2002] No. 629) regarding the tax calculation method for the "double salary system" has been discontinued.
The "double salary system" tax calculation method refers to the scenario where state organs, public institutions, enterprises, and other entities implement the "double salary system" (in accordance with relevant state regulations, the entity issues an additional month's salary to its employees). The "double salary" thus obtained by an individual is separately calculated and levied as individual income tax as a month's salary and wage income.
After the discontinuation of the "double salary system" tax calculation method, entities may either merge the additionally issued month's salary into the current month's salary for tax calculation or include it in the "annual lump-sum bonus". The "annual lump-sum bonus" refers to, in the month when the year-end lump-sum bonus is issued, dividing the bonus by 12 months and determining the applicable tax rate and quick deduction based on the quotient.

Illustrative Case:
Assume Wang's monthly salary is 3,000 yuan, and the company issues him a double salary of 3,000 yuan in the current month.

Tax Calculation under the Old "Double Salary" Method:
Salary: 3,000 yuan. After deducting the 2,000 yuan threshold, the taxable amount is 1,000 yuan, which applies to the九级超额累进税率 (nine-bracket progressive tax rate) of 10% with a quick deduction of 25. The specific formula is: (3,000 - 2,000) * 10% - 25 = 75 yuan
Double Salary: 3,000 yuan, which applies to the九级超额累进税率 (nine-bracket progressive tax rate) of 15% with a quick deduction of 125. The specific formula is: 3,000 * 15% - 125 = 325 yuan
Then, Wang's individual income tax payable for the current month is: 75 + 325 = 400 yuan

Tax Calculation under the New Method of Merging into Current Month's Salary:
Income: 6,000 yuan. After deducting the 2,000 yuan threshold, the taxable amount is 4,000 yuan, which applies to the九级超额累进税率 (nine-bracket progressive tax rate) of 15% with a quick deduction of 125. The specific formula is: 4,000 * 15% - 125 = 475 yuan

Tax Calculation under the New Method of Apportioning as "Annual Lump-Sum Bonus":
First, divide 3,000 by 12 to get the quotient (3,000 ÷ 12 = 250 yuan) to find the applicable tax rate. The tax rate corresponding to 250 yuan is 5%. The calculation process for individual income tax payable is as follows: 3,000 × 5% = 150 (yuan). Wang's individual income tax payable on the year-end double salary is 150 yuan, and the tax payable on the current month's salary is (3,000 - 2,000) * 10% - 25 = 75 yuan. The total tax payable for the current month is 150 + 75 = 225 yuan.

The tax calculation method stipulated in 2005, which apportions the annual lump-sum bonus to 12 months to determine the applicable tax rate, has already treated year-end salary increases as a form of annual lump-sum bonus for tax calculation. Therefore, the cancellation of the original "double salary system" tax calculation method this time is only a cleanup of past old policies. Individuals obtaining year-end salary increases shall still calculate and pay tax in accordance with the apportionment tax calculation method introduced in 2005, and there is no change in the individual tax burden (see the previous example for details). Specifically, for taxpayers who only have year-end salary increases (double salary) and no annual lump-sum bonus, the year-end salary increase (double salary) shall be implemented in accordance with the apportionment tax calculation method for the 2005 annual lump-sum bonus; for taxpayers who have both year-end salary increases (double salary) and annual lump-sum bonus, the two incomes shall be merged and the apportionment tax calculation method for the annual lump-sum bonus shall apply. Recently, some high-income enterprises have separately apportioned and calculated the withholding of individual income tax for year-end salary increases (double salary) and annual lump-sum bonuses, which violates the policy provisions on annual lump-sum bonuses in 2005. The clarification and cancellation of the original "double salary system" tax calculation method this time is a requirement for the regular cleanup of outdated or invalidated documents, and also considers regulating the tax system, ensuring fair tax burden, and adjusting high incomes in response to the above-mentioned non-compliant behaviors. It will not increase the burden on ordinary wage earners.