It is reasonable to deduct social security fees one month in advance.

Legal analysis: social security is paid at the beginning of the month, and the company pays it first, and then deducts it from the employee's salary.

If one month's social security fee is deducted, it may be that the employee's salary this month will be paid next month, and the employee will know to deduct the social security fee when paying the fee. For example, the social security in January is paid by the company for one month, and the part paid by the individual for one month is deducted from the salary in January, and the salary in January is paid in February, so the social security deducted from the salary in February is actually deducted for one month.

Legal basis: Article 15 of the Provisional Regulations on Wage Payment in People's Republic of China (PRC), the employer shall not deduct the wages of workers. Under any of the following circumstances, the employer may withhold the wages of the workers:

(1) Personal income tax withheld and remitted by the employer;

(two) social insurance premiums withheld by the employer and borne by the individual workers;

(3) The alimony and maintenance expenses required to be withheld by the court's judgment or ruling;

(four) other expenses that can be deducted from the wages of workers as stipulated by laws and regulations.