Offside in football means a player is ahead of both the ball and the second-last opponent, in the opponents' half, at the exact moment a team-mate plays the ball, and then becomes involved in play. Being in an offside position alone is not an offence. The referee only penalises a player who touches the ball, interferes with an opponent, or gains an advantage from that position.

The rule is Law 11 of the Laws of the Game, written by the International Football Association Board (IFAB). It exists to stop attackers from waiting beside the goal for a long ball, and it shapes how teams attack and defend.

What is the offside rule in football?

A player is in an offside position if three things are all true when a team-mate plays the ball. First, the player is in the opponents' half of the pitch. Second, any part of the player's head, body or feet is nearer to the opponents' goal line than the ball. Third, that same part is nearer to the goal line than the second-last opponent.

The second-last opponent is usually the goalkeeper plus the last outfield defender. Hands and arms do not count when judging offside, because a player cannot legally score with them. For this purpose, the arm is taken to begin at the bottom of the armpit. A player who is level with the second-last opponent, or level with the ball, is onside.

When does offside become an offence?

Standing in an offside position is legal. An offence happens only when the player becomes involved in active play in one of three ways: by playing or touching a ball passed or touched by a team-mate, by interfering with an opponent, for example by blocking the goalkeeper's view, or by gaining an advantage from the position, for example when the ball rebounds from a goalpost, the crossbar or an opponent.

Offside is judged at the moment the ball is played, not when the attacker receives it. A striker who is level with the last defender when a team-mate plays a through ball can therefore run beyond the defence and receive the pass legally.

When can a player not be offside?

There is no offside offence when a player receives the ball directly from a goal kick, a corner kick or a throw-in. A player also cannot be offside in their own half of the pitch, even if they are standing beyond every opponent. When an offside offence is given, the referee awards an indirect free kick to the defending team, taken from where the offence happened.

How does VAR check offside?

In top competitions, the video assistant referee checks offside in the build-up to a goal. Officials look at the frame in which the ball was played and compare the positions of the attacker and the second-last opponent. Because the margins can be tiny, these checks often come down to a shoulder or a toe ahead of the defensive line, which is why offside remains one of the most debated parts of the modern game.

Offside rule FAQs

Can you be offside in your own half? No. A player cannot be in an offside position in their own half.

Is a player offside if they are level with the defender? No. Level with the second-last opponent means onside.

Do arms count for offside? No. Only the head, body and feet count, because those are the parts a player can legally score with.

What happens when offside is given? The defending team is awarded an indirect free kick from the place of the offence.

For the full wording, see All About Football's guide to the offside rule and Good Sport's explanation of offside.