What is the ruling on working for a company that sells lands and factories on an installment basis with an increase in price based on the central bank interest rate, knowing that the contract includes a late payment penalty, and that profits are invested in banks or treasury bills? Is it permissible for me to continue in my job, which involves calculating installments and penalties and collecting them?

Increasing the price in a deferred sale is permissible if the price is known at the time of the contract, because time has a share in the price. However, imposing a financial penalty for late payment of an installment is forbidden interest (riba). Working in a company whose activity is permissible is allowed, provided one avoids direct involvement in forbidden matters such as writing down or collecting interest (riba). An exception is made for dire necessity if a person cannot find other work to support themselves and their dependents, with the obligation to strive to find permissible work.