Baikan means selling government posts.
In ancient and medieval Japan, the baikan system was introduced as an official system to rescue courtiers without posts. In other parts of the world, government posts were sold in order to increase revenue when governments faced a financial predicament.
These days, the term, Baikan, refers to gaining a government post by bribe.
Baikan in Japan
Baikan meant to give a certain government post to Sani (courtier without post) who paid ninryo (fee for getting an official rank). Nenkan (a right granted as a stipend to members of the Imperial family (including the emperor), consorts of the emperor, some Court nobles, and so forth to nominate a person for a certain government post conferred to them on the occasion of the annual installation of them as government officials) and jogo (ninkan) (recruiting officials for court works and spending the money they paid for the post for the work expenses) were examples of Baikan.
In ancient and medieval Japan, the government made post-less courtiers (Sani) with ranks lower than Rokui (Sixth Rank) serve for Saniryo (the office controling Sani, courtier without post) in order to help and give them chances for appointments or promotions. The government had a policy that those courtiers would get a chance for appointments when they worked long enough for promotions. Even after the number of posts was determined, the following chances were introduced: supernumerary courtiers bought 'labour' by paying shokurosen (money paied for getting an official rank). That established the Baikan system.