Where applicable, a club’s application to register a player has to be accompanied by evidence to allow the League to demonstrate that the player may take up employment in the UK.
The League will not confirm the player is eligible to play for the club applying to register him until it has received such evidence. (Rule U.13)
Players with passports from outside the European Union and the European Economic Area need permission to work in the UK.
A club need to have applied for a permit prior to the window closing.
The UK Home Office has a points-based system based on which clubs must apply to The FA for a "Governing Body Endorsement" for such players. (See p551 of the Premier League Handbook 2018/19 (Download PDF, size: 8.39MB))
If the player does not automatically meet these criteria, the club can request an FA Exceptions Panel consider the player’s experience and value in order to determine whether a Governing Body Endorsement should nevertheless be granted.
Part 1: What is the deal sheet in transfers?
Part 2: How do clubs begin the process of completing a player transfer?
Part 3: What is the Premier League's role in transfers?
Part 4: What is FIFA's Transfer Matching System?
Part 6: Rules governing the third-party ownership of players
Part 7: Is a fax machine used for transfers?
Part 8: How many loans are allowed by Premier League clubs?