The July salary can be specified for separate tax calculation. The specific operation method is as follows.

1. First, you need to fill in your personal information and income in the personal income tax return.

2. When filling in salary income, you can choose to specify July salary for calculation. The specific operation is to fill in the salary income amount in July in the "Wage and Salary Income" column, and select "Monthly Specified Tax Calculation" in the "Tax Calculation Method" column.

3. Calculate the amount of personal income tax you need to pay according to the personal income tax calculation formula.

4. It should be noted that separate tax calculation needs to meet certain conditions. For example, both husband and wife must be Chinese citizens and register for tax payment at the same tax authority. In addition, the calculation methods and tax rates of personal income tax will also vary according to different income situations and policy changes. Therefore, before taking specific actions, it is recommended that you first understand the relevant policies and regulations, or consult the staff of the local tax authority.