Here is the relevant ruling from FIFA make of it what you will

Players may only be registered to play with a national association during one
of two registration periods per year, as laid down by the national association for this
purpose, with a limit of one transfer of registration per player in the same sports
season in a period of 12 months. One of these periods (?registration periods?) is
fixed for the end of the season and another period for the middle of the season.

Posted By: Real men wear yellow, Aug 14, 14:27:59