The insurance rate is 18.3%, and you'll pay half of it
If you are an employee, your employer will issue a notification slip in September as the insurance premium is set based on the salary you received between April and June of the same year. The amount of contribution is valid until August of the following year. Exceptional cases include switching jobs or dramatic changes in salary.
Suppose you are hired by a corporation and therefore belong to the Employees’ Pension (Kosei Nenkin, or 厚生年金). In that case, your social insurance premium is determined based on the table right (the FY2022 version. Source: Japan Pension Service).
The overall amount of the Employees’ Pension premium is divided by an employee and an employer. The insurance rate is 18.3%; therefore, your premium is half of it, which is 9.15%.
Look for your case in the table
More specifically, look for the amount of your salary in column (2) of the table below (Source: Japan Pension Service. The image is arranged by the author based on the original source material for easier understanding). You’ll find your salary group in column (1), which becomes the base of the calculation. Column (3) shows the amount of the group with the insurance rate of 18.3%, and the right column (4) is half of it which is deducted from your salary as a pension premium.