The expanded FIFA Club World Cup takes place in the United States from June 14 to July 13.
Along with adding more elite football to an already packed schedule for some of Europe's leading clubs, the global tournament will also be ongoing as transfer business rumbles on.
As such, FIFA announced changes to transfer and player registration rules for participating clubs and confirmed those plans on May 21.
Will Trent Alexander-Arnold be in action in the U.S. after leaving Liverpool to join Real Madrid on a free transfer? Similarly, why are Manchester City in such a hurry to bring in new signings?
Here's everything you need to know about the 'split' transfer window.
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FIFA Club World Cup transfer window, explained
Usually, the transfer window for the majority of European clubs would not open until mid-to-late June or early July following the conclusion of the domestic season. However, because of the expanded Club World Cup taking place across June and July, FIFA decided to change the regulations for 2025.
Teams taking part in the tournament will be able to sign players prior to the competition in an "exceptional registration window", rather than just the usual period. This "split" window means they can bring in or sell players before the tournament starts, if they so desire.
When is the extra FIFA Club World Cup transfer window?
The extra registration period runs from June 1-10, 2025. FIFA announced this step last October and confirmed the dates on May 21, 2025.
There will also be an in-competition window between June 27 and July 3 "according to specific limitations" for teams who progress to the knockout stages to register players in time for those fixtures.
In response to FIFA's ruling, the Premier League and La Liga have fallen into line by confirming an extra transfer window for the first 10 days of June that applies to all their clubs, with the regular transfer window then opening from June 16 until the end of August. That means all teams in those leagues can conduct business at the same time, rather than only those in the Club World Cup.
When is the FIFA Club World Cup transfer window deadline?
The pre-tournament window closes at 7 p.m. BST / 2 p.m. ET on Tuesday, June 10.
Participating teams that wish to have new signings available for their group games must have these players registered by this deadline.
Why is there an extra transfer window for the Club World Cup?
FIFA identified the need for the change because of the way player contracts are structured in the European leagues.
Standard contracts commence on July 1 and conclude on June 30 — a usually frictionless arrangement because their clubs are typically not in competitive action.
However, it means players can now fall out of contract during the Club World Cup. Clubs now have the option to give such players a short-term deal during the mid-tournament window if their wider futures have not been resolved.
In the Alexander-Arnold example, his free transfer would usually mean him officially becoming a Real Madrid player on July 1.
However, the pre-tournament window allowed Madrid to negotiate a deal with Liverpool for his early release, under which they paid the €10million (£8.4m/$11.4m)
The Premier League and La Liga decided to split their transfer windows between their traditional periods and the new Club World Cup slot, meaning all clubs in those leagues can conduct business rather than only those taking part in the tournament. That means those teams playing do not get an unfair advantage over their domestic rivals by being allowed to complete deals before others.