Is the interest paid to the Social Security Corporation to obtain a retirement salary considered usury, and is the resulting retirement salary unlawful?

If the fund fulfills all the required regulations and is based on the intention of cooperation (mutual aid), then there is no objection to the fund covering cases such as compensation for a married woman, or a retirement pension for someone who has reached a certain age, even if it exceeds the amount contributed. This is not usury (riba), as it is not necessary for a participant to receive back exactly what they paid in.

Cooperative insurance is permissible because: 1. It is a contract of donation (tabarru') that aims at cooperation in distributing risks and bearing responsibility. 2. It is free from both types of usury (riba). 3. The participants' ignorance of the exact benefit they will receive does not cause harm because they are donors. 4. It is permissible to invest the collected premiums to achieve the purpose.

However, if the fund is based on exchange (mu'awadah) rather than donation (tabarru'), then participating in it is impermissible due to its inclusion of ignorance (Jahalah), usury (riba), and ambiguity (Gharar). Whoever has participated in it must repent, and it is not permissible for them to benefit from it by more than what they contributed.