After signing a player, how soon can he play for his new team?

Question

In football, how soon after signing a player may he play for his new squad? Liverpool are in the middle of signing Mario Balotelli from Milan in the Italian Serie A. It is reported, that if the deal goes through, he could be available to play this upcoming Monday (4 days).

Presumably different leagues have different protocols, and if that's the case then the English Premier League could be focus since that is to be his destination if the transfer does go through.

Is a recently transferred player able to play "instantly" for his new squad? Or is there a period of time before the player may start a game?

Answer 1

There is a time deadline before which he should have signed for the new club so that the player becomes eligible to play immediately(not exactly immediately, but i will explain with an example.)

Like in the case of Balotelli, if he wants to play against Man City on monday, he must be registered as a Liverpool player by friday i.e he must have signed for liverpool by friday noon.

Balotelli could make his debut for Liverpool at City in the Premier League on Monday but would have to be registered by noon on Friday and that appears unlikely.

Source for the above text is here

Answer 2

Once the transfer goes through a player may play for his/her new club as soon as s/he gets licence to practice professional football. The licence is usually given by the domestic football association.

The FA will consider a number of parameters prior to issuing a licence for a particular player, these parameters include (but not limited to) any roster restrictions that may apply such as:

• total number of players registered for the league competition
• eventual limitations on number of foreign/non-EU players at the club
• eventual work-permit limitations (primarily in the UK, for non-EU nationals)