What Is Offside in Soccer? (The Rule Explained)

A player is offside in soccer if, at the moment a teammate plays the ball, they are in the opponents’ half and nearer to the opponents’ goal line than both the ball and the second-to-last defender, and they then become involved in active play. The rule, defined as Law 11 by the International Football Association Board (IFAB), exists to stop attackers from simply loitering near the goal waiting for a pass.

Offside position versus offside offense

The most important distinction is that standing in an offside position is not against the rules. A player is only penalized if, while in that position, they get involved in active play. That can mean playing or touching a pass from a teammate, interfering with an opponent, or gaining an advantage from being there. If an attacker is offside but never touches the ball or affects the play, no offense has occurred. This is why you sometimes see a player clearly ahead of the defense with no flag raised.

What counts as an offside position

A player is in an offside position if any part of their head, body, or feet is in the opponents’ half and closer to the goal line than both the ball and the second-to-last opponent. The second-to-last opponent is usually the last outfield defender, because the goalkeeper is typically the last player. Hands and arms do not count, since a goal cannot be scored with them. Judging this comes down to the exact instant the ball is played by the teammate, which is why offside calls are so tight.

When you cannot be offside

There are clear exceptions. A player cannot be offside in their own half of the field. A player level with the second-to-last opponent, or level with the ball, is onside. And there is no offside offense if the player receives the ball directly from a throw-in, a corner kick, or a goal kick. These situations remove the offside judgment entirely, which is one reason attacking teams value corners and throw-ins in dangerous areas.

How offside is judged

Offside is called by the assistant referee, who runs the sideline and watches the second-to-last defender, and confirmed by the central referee. Because the decision hinges on a single frozen moment, it can be extremely fine, sometimes a matter of a shoulder or a foot. Many competitions now use video review to check tight calls, but the underlying law is unchanged: position at the moment the ball is played, plus involvement in the play.

The three ways of being involved

Because position alone is not enough, the laws spell out what “involved in active play” means. The first is interfering with play, which simply means playing or touching a ball passed or touched by a teammate. The second is interfering with an opponent, such as blocking the goalkeeper’s line of sight, challenging for the ball, or clearly making a movement that deceives a defender. The third is gaining an advantage, for example collecting the ball after it rebounds off the post, the crossbar, or an opponent while the player was in an offside position. Any one of these turns an offside position into a punishable offense.

The deliberate-play exception

There is an important nuance when a defender touches the ball. If an attacker in an offside position receives the ball because a defender deliberately played it, the attacker is generally not penalized, because the defender chose to play the ball. But this does not apply to a deliberate save: if a defender or goalkeeper makes a save and the ball falls to an offside attacker, offside can still be called. IFAB clarified these deliberate-play guidelines to help referees separate a controlled defensive action from a rushed deflection.

Why the rule matters

Offside shapes how soccer is played. Defenses use it as a weapon, stepping up together to catch attackers ahead of the last defender in what is called an offside trap. Attackers, in turn, time their runs to stay level or behind the ball until the pass is made. This constant cat-and-mouse is a core part of the sport’s tactics. If you are learning the rules, it pairs naturally with understanding soccer positions, since defenders and forwards are the players most affected. It also connects to scoring feats like a hat-trick, where an attacker’s timing against the offside line often makes the difference. For how a drawn knockout game is settled, see our guide to extra time.