NFL substitution rules: All you need to know in 2023

The NFL allows teams to substitute players at will. Throughout the course of a game, they are able to switch up as many players as they choose. Because of this, each player now plays a specific position and has become specialized in his role for the side.

Each team consists of three distinct units: special teams, which only enter the game during kickoffs, punts, and field goals; offense, which consists of members who participate only when their team is in ownership of the ball; and defense, which consists of players who take the field to thwart the offense of the opposition.

Overall, a team may only have 11 players on the field at once, and those who have been substituted out are not allowed to stay on the field. Staying on the field after being substituted out will be considered as a foul on play and will carry penalties.

NFL fans should take note of the following important substitution guidelines:

#1 - In the NFL, substitutions are allowed to happen indefinitely, but only when the ball is out of play.

#2 - A player who has been substituted out is not permitted to reenter the field after a snap. An 'illegal substitution' will be triggered if he does.

#3 - Teams can only make substitutions on the field.

#4 - Each player that is substituted out has to exit the game entirely before the next snap.

#5 - When a player from the offensive side speaks with the huddle and is not yet substituted, he has to be sent in for the following play.

NFL substitution rules: What is illegal substitution?

A team will be penalized if, at any stage throughout the game, it has more players than is necessary. If the offensive team has more than 11 men on the field at any point between the creation of the huddle and when it breaks, they face a penalty for unlawful substitution.

If there are more than 11 players on the field at the snap of the ball for the defending side, even if one of them is trying to exit the field of play at the time, an illegal substitution call may be made. An illegal substitution results in a replay of the down and a loss of five yards.

Teams frequently become the victims of illegal substitutions after some confusion concerning a player who is meant to depart the field of play after he has been substituted out. This primarily occurs on offensive plays, when a player may remain in the huddle without realizing they have been changed.

The quarterback typically contributes to preventing this uncertainty by waiting to enter the huddle until all substitutes have been made.