Is it permissible for an employee to increase the value of their subscription to the retirement insurance system in order to increase their retirement pension upon retirement, knowing that the system allows this and currently deducts 9% of the salary?

For subscribing to the retirement insurance system, there are two forms: The first is compulsory, as practiced in government companies. There is no sin upon the employee in this, and it is considered a right that the ruler has committed to for his subjects. The second is optional, and it is stipulated therein that the insurance must be permissible cooperative insurance, not prohibited commercial insurance.