Is the commission paid in exchange for favoring a specific company in business dealings permissible or forbidden (halal or haram)?

It is not permissible for an employee to take a commission for their agreed-upon work unless authorized by their employer. However, for work that is not part of their primary duties, it is permissible for them to take a commission, even without the company's knowledge if the work is outside official working hours. The Permanent Committee has issued a fatwa (definition) stating the impermissibility of a middleman taking a commission from another company in exchange for dealing with it on behalf of the company he works for, because it is likely to harm the company in terms of price or quality of goods.