What Is Offside? Soccer's Most Debated Rule, Explained

If there's one rule in soccer that generates debate in every match, it's offside. Entire stadiums erupt in joy over a goal, only to have celebrations die down seconds later when the assistant referee raises their flag and the goal is disallowed. Why? Who was ahead? How is it determined? In this article we explain it clearly, with examples and an illustration.

The Official Definition

According to FIFA's Laws of the Game, a player is in an offside position if any part of their body — except hands and arms — that can play the ball is closer to the opponent's goal line than both the ball AND the second-to-last player of the opposing team. The second-to-last defender is almost always the last outfield player, since the goalkeeper is usually the furthest back.

The Key Moment: When the Ball Is Played

A very common misconception is that offside is evaluated when the attacker receives the pass. In reality, the critical moment is when the teammate touches the ball to pass it. If at that precise instant the attacker is ahead, they are offside even if they manage to return to a legal position before receiving the ball. That said, being in an offside position is not itself an infringement — only if the player actively participates in play.

Illustration: Onside vs. Offside

The diagram below shows two scenarios. On the left side (✓ ONSIDE), the attacker (A, in red) is behind the line of the second-to-last defender at the moment of the pass — the player is in a legal position. On the right side (✗ OFFSIDE), the attacker is ahead of that line at the moment of the pass — an illegal position.

When Does Offside NOT Apply?

• •Goal kicks: when the goalkeeper kicks the ball from their area, offside cannot be called on that play.
• •Throw-ins: when the ball is thrown in from the sideline, offside does not apply.
• •Corner kicks: there can be no offside on corner kicks.
• •If the ball comes from an opposing defender: if an opposing defender touches the ball (even unintentionally), it resets the offside.

Being Offside ≠ Committing an Infraction

A player can be in an offside position without the referee whistling. It's only penalized when that player actively participates in play — that is, when they receive the ball, obstruct the goalkeeper, or clearly influence the game. If the pass goes to another teammate who is in a legal position, the first player's offside doesn't matter. This distinction is key to understanding why the referee sometimes waits before raising the flag.