Question: Is what people do when dealing with officials – namely, giving some money to the official so that he will complete the transaction – considered among the forbidden forms of bribery?
Answer: That is not among the forbidden forms of bribery. The forbidden bribery is what a person pays in money to the judge or the official in order to take the right of someone else.
As for what a person pays in money in order to take a right that belongs to him, or so that the employee will complete his transaction, or in order to gain him as a client, or for similar purposes, then there is no objection upon the one who pays the money and no sin upon him.
Source: Min Thimār al-ʿIlm wa al-Ḥikmah vol.2