Champions League clubs face another important deadline immediately after completing their summer transfer business.
Teams competing in the 2026/27 UEFA Champions League league phase must submit their main player lists by 23:59 CET on September 2, meaning managers now have to decide exactly who will be eligible to represent them in Europe's leading club competition.
For clubs that completed major deadline-day signings, this is particularly important. Signing and registering a player domestically does not automatically make that player eligible for the Champions League. The player must also meet UEFA's registration requirements.
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What Is the Champions League Squad Deadline?
Every Champions League club must submit players through two registration categories known as List A and List B. List A is effectively the club's main Champions League squad. UEFA allows a maximum of 25 players on List A, and at least two of those players must be goalkeepers.
However, clubs cannot simply fill all 25 positions with any players they choose. UEFA's locally trained-player rules also have to be satisfied. That makes squad registration more complicated than selecting a club's best 25 players.
Why the Eight Locally Trained Places Matter
At least eight List A positions are reserved for locally trained players. UEFA divides those players into two categories. A club-trained player must have spent the required development period between the ages of 15 and 21 registered with his current club.
An association-trained player meets a similar development requirement but can have been trained by another club belonging to the same national association. Only four of the eight locally trained positions can be filled exclusively by association-trained players.
This effectively encourages Champions League clubs to maintain players who developed within their own academy systems. It is also important to understand that the rule is not simply a requirement to name eight homegrown players and then replace missing ones with other senior players.
If a club does not have enough eligible locally trained players, its maximum List A size is reduced. For example, a shortage of qualifying homegrown players can leave a club with fewer than 25 available List A positions.
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Why Some Young Players Do Not Need a List A Place
List B gives clubs considerably more flexibility with young players. For the 2026/27 competition, qualifying players generally need to have been born on or after January 1, 2005, and must also satisfy UEFA's requirements regarding how long they have been registered with the club.
There is no equivalent 25-player limit on List B. Eligible academy players can therefore be added during the season without occupying valuable places on List A.
This is why supporters may sometimes see a young player feature in the Champions League even though his name appears to be missing from a club's widely reported 25-man squad.
He may instead be registered through List B. However, being young alone is not enough. A recently signed young player may not qualify because UEFA also requires a minimum period of registration with the club.
What Happens to Deadline-Day Signings?
This is one of the most relevant issues following the closure of the summer transfer window. A player who completed a transfer before the domestic deadline can play in the Champions League league phase as long as his club also registers him with UEFA before the September 2 deadline and he is otherwise eligible.
That means clubs that completed major signings on September 1 have had little time between finishing those transfers and finalising their European squads.
By contrast, any player joining after UEFA's List A deadline cannot simply be added to the league-phase squad later. That distinction is important because domestic eligibility and Champions League eligibility operate under separate registration systems.
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Can Players Who Played European Qualifiers for Another Club Still Be Registered?
Yes. The old idea of players being permanently "cup-tied" after appearing for another club earlier in the same European season no longer works in the same way.
UEFA allows a player who appeared for another team during Champions League, Europa League, or Conference League qualifying to be registered by a different club for the Champions League league phase.
Therefore, playing in a European qualifier during the summer does not automatically prevent a new signing from representing his new club in the league phase.
Can Champions League Squads Be Changed After September 2?
Clubs have limited opportunities to make changes. Eligible List B players can continue to be registered during the competition, provided the requirements are satisfied. There are also specific exceptions involving injuries.
During the league phase, and up to Matchday 6, a club can temporarily replace one List A outfield player suffering from a long-term injury or illness expected to last at least 60 days. The replacement player must already have been registered with the club before the September 2 List A deadline.
Goalkeepers have separate replacement provisions, including situations involving long-term injuries. These rules prevent clubs from freely rebuilding their European squads during the league phase while still providing some protection when serious injuries occur.
What Happens Before the Knockout Phase?
Clubs that progress beyond the league phase get another opportunity to adjust their squads. UEFA permits qualifying teams to register up to three new players before the knockout phase, with the deadline set for February 4, 2027.
Those additions could include January signings or players omitted from the original league-phase List A. The overall 25-player limit and locally trained-player requirements still apply. This makes January recruitment particularly important for clubs that identify weaknesses during the league phase.
Why the September 2 Deadline Matters
The squad-registration deadline can influence Champions League campaigns before the first match is even played. Clubs must balance several factors: which senior players they expect to use regularly, which academy players qualify for List B, the number of locally trained players available, and whether injured players are worth keeping on List A.
Deadline-day transfers make those decisions even more significant. A club may have assembled an expensive squad during the summer, but UEFA's registration rules ultimately determine which players are actually available in Europe. For supporters, that means the official Champions League player lists are worth watching closely.
The most interesting development may not simply be which new signings are included, but also which established players are left out. With the league phase beginning on September 8, clubs now have their final opportunity to establish the core squads they will rely on during the opening stage of their Champions League campaigns.
Via: UEFA