Most football leagues around the world follow FIFA’s Regulations on the Status and Transfer of Players (“RSTP”) to control the player transfer system through rules that balance player and team interests.
The current version of the RSTP (referred to by FIFA as simply the “Regulations”) is dated as of December, 2017.
FIFA also made certain amendments to these regulations, which took effect on June 1, 2018.
An example is provided by the 2018 transfer of the Spanish goalkeeper Kepa from Athletic Bilbao to Chelsea Football Club. The transfer came about as a result of the London side paying the keeper’s rescission clause (a/k/a release clause) in his contract, which was on the order of €78 million (£71 m).