In association football, a player who has appeared for a football club during a knockout cup but subsequently transfers to another club is ineligible to play for the new club in the remainder of that season's cup competition. Such a player is said to be cup-tied, i.e. tied to their original club for the duration of the cup tournament. They become eligible for their new club in the following season.
The rule is intended to prevent teams which progress in the competition buying talented players from teams which have already been eliminated, in an attempt to increase their chances of winning. It also discourages players whose chief priority is winning a trophy from requesting a transfer once their team has been eliminated from the competition. Since the introduction of transfer windows, which the cup-tied rule pre-dates, some have criticised the rule as outdated. Nevertheless, it remains widely applied.
Almost all cup competitions worldwide operate a cup-tied rule, but leagues do not (as leagues do not eliminate teams during the season). Cup-tied players are only prevented from playing in that specific competition, so for example a player who is cup-tied in the FA Cup may still be eligible to play in the League Cup (or vice versa). UEFA competitions are an exception: because teams can switch between the UEFA Champions League and UEFA Europa League during the season, UEFA has a more complex system for determining whether a player is cup-tied in one or both of those competitions.
The cup-tied rule
In almost all domestic and international club cup competitions, any player who makes an appearance for a club at any stage of the competition is "tied" to that club for all future matches during that season in the same competition. This prevents a wealthy team still in the competition from gaining an unfair advantage by signing talented players from clubs that may have lost out in earlier rounds, in an attempt to increase their cup chances.
The rule applies to individual cup competitions, such that a player who plays in the English FA Cup, but not the EFL Cup, for example, is cup-tied only in the former competition. If the player signs for a new club in the same season, they are thus eligible for the EFL Cup but not the FA Cup.
Breaching the cup-tied rule can result in a result being declared invalid, with serious consequences for the offending club. Governing bodies usually reserve the right to waive the rule but do so only in exceptional circumstances.
UEFA competitions
UEFA operates European club football competitions, primarily the UEFA Champions League and UEFA Europa League. UEFA's regulations state that, with a few exceptions, players who play in any European club competition are subsequently cup-tied with respect to all European football for the remainder of the season. On 27 March 2018, UEFA announced that it would phase out the cup-tied rule for the Champions League and Europa League, starting in the 2018–2019 season.
The main current exception is the UEFA Super Cup, contested by the winners of the previous seasons' Champions League and Europa League. As this is effectively a prestige friendly with only one round, the cup-tied rule is seen as unnecessary. Representing a club in this fixture does not affect a player's eligibility in other UEFA competitions. Similarly, cup-tying did not apply to matches in the now-defunct pre-season UEFA Intertoto Cup, up to the semi-final round.
A further exemption applies: one player per club who would normally be cup-tied can be registered and eligible to play, so long as their previous club did not field that player in the same competition. This means that players can represent two clubs in the Europa League and Champions League, but only a maximum of one player per club. However, if the first club switches into the same competition (e.g. transfers from the Champions League to the Europa League through finishing third in the group stage), the transferred player becomes ineligible. This can lead to some complex situations.
Criticism
The cup-tied rule comes in for criticism from various fans and media pundits, particularly when a high-profile player is ineligible for significant matches. Some argue that the rule is antiquated and that since the introduction of transfer windows, clubs cannot buy players solely for cup matches, but will only do so for the league, where there is no cup-tied rule.