Offside vs Onside — What's the Difference?

Onside and offside describe a player's position relative to the defensive line at a specific moment. The difference comes down to one reference point and one instant in time — and getting both right is why offside decisions are so frequently debated.

| | Onside | Offside | |---|---|---| | Position | Level with or behind the second-last defender | Any legal body part ahead of the second-last defender | | Is it an offence? | Not applicable | Only if involved in active play | | Moment that matters | When the ball is played, not when it is received | Same | | Arms/hands count? | No | No |

What does "level" mean in offside?

Level means equal — if any part of the attacker's legal body is level with the second-last defender, that player is onside. The law requires the attacker to be ahead of the second-last defender to be in an offside position, and level does not count as ahead.

The second-last defender is almost always the last outfield defender. The goalkeeper typically counts as the last defender. If there is no goalkeeper (they have been sent off and no substitute goalkeeper is on), the rule still applies to whichever two players are furthest back.

When exactly is the offside position judged?

The moment the ball is played — the instant a teammate's foot or head makes contact and releases the ball — is the only moment that matters. Not when the player receives the ball. Not when they start their run.

A player can be in an offside position when the ball is played and sprint to an onside position before receiving it; the flag should still go up. Conversely, a player who is onside when the ball is played can drift offside before receiving without any offside call, because the position at the moment of the pass is what counts.

This is why VAR freezes the frame at the exact moment of the kick.

Can you be onside and still cause an offside decision?

Yes — through the involvement rule. Being in an offside position is not automatically an offence. A player in an offside position who does not interfere with play, with an opponent, or with the ball commits no offence. But if they then interact with play — receiving the ball, blocking a goalkeeper's line of sight, or challenging for a rebound — they are penalised.

Similarly, a player can be onside but accidentally play the ball to a teammate who is in an offside position and has become actively involved. The onside player's action triggered the situation, but the offside player is penalised.

Learn more in the offside rule lesson, active vs inactive offside, offside controversies, and try the offside scenario engine.