In the Championship, League One and League Two, clubs must have a minimum of eight homegrown players registered in their squad. For a league game, clubs must name at least seven homegrown players in their matchday squad. A homegrown player is someone who has been registered with their current club, or any English or Welsh club, for three seasons or 36 months before their 21st birthday, or before the end of the season in which they turn 21.
These rules are only enforced in league matches, not in the FA Cup, EFL Cup or EFL Trophy. The Premier League operates its own separate system of squad and homegrown rules.
The classification can apply even to players who are not English or Welsh. In Watford's recent 2-0 win over Charlton Athletic, only Mattie Pollock and Marc Bola were listed as English in the Hornets matchday squad. Hector Kyprianou (Cyprus), Jordan Zemura (Zimbabwe), Daniel Bachmann (Austria), Stephy Mavididi (Democratic Republic of Congo) and Amin Nabizada (Afghanistan) all represent other countries internationally, but are classed as homegrown because of where they played their youth club football.
Once an EFL club has submitted its squad list after the summer transfer window, it must name at least one club-developed player per match on its squad list or team sheet. If it fails to do so, it is permitted one fewer bench player for that game: eight substitutes instead of nine in the Championship, or six instead of seven in League One and League Two. Players aged under 21 do not count towards squad lists in any of the three leagues, and goalkeepers are excluded from the League One and League Two squad lists.
Source: BBC Sport Football · Summarized by HeadlinesBriefing