What term refers to illegal payments received in exchange for preferential treatment or services?

The term that refers to illegal payments received in exchange for preferential treatment or services is "kickbacks." Kickbacks involve the unethical practice where an individual or organization receives a payment to facilitate or encourage certain actions, typically in a business context. This might happen in situations where a person in a position of authority favors a particular contractor, supplier, or service provider in exchange for part of the payment being returned to them. The essence of a kickback lies in the illicit nature of the transaction and the expectation of a reciprocal benefit for the payer, which violates legal and ethical standards.

Bribes, while similar, typically refer to payments made to secure broader illegal or unethical advantages, which can include kickbacks but aren't confined to preferential treatment in business dealings. Service fees and incentives, on the other hand, are generally legitimate and lawful compensations for services rendered or as part of a motivated arrangement to boost performance, and do not carry the implication of wrongdoing or corruption.