The Offside Rule Explained Simply: A Complete Guide for Referees and Fans

Master the offside rule with clear explanations, diagrams, and real match scenarios. Everything you need to know about Law 11.

The offside rule is probably the most debated law in football. I have watched experienced referees and fans argue about it for years, and even now, the nuances trip people up. Let me break it down in a way that actually makes sense.

The Basic Rule

A player is in an offside position if:

  1. They are in the opponents’ half of the pitch
  2. They are nearer to the opponents’ goal line than both the ball AND the second-last opponent

Being in an offside position is not an offence in itself. The offence only occurs if the player becomes actively involved in play.

When is it Actually Offside?

A player in an offside position is penalised if, at the moment the ball is played by a teammate, they:

  • Interfere with play - by playing or touching a ball passed or touched by a teammate
  • Interfere with an opponent - by preventing them from playing the ball, clearly obstructing their line of vision, or challenging them for the ball
  • Gain an advantage - by playing the ball that rebounds off a post, crossbar, or opponent

Common Misconceptions

“Level is Onside”

Correct. If any part of a player’s body that can legally play the ball (head, body, feet, not arms) is level with or behind the second-last opponent, they are onside.

“You Cannot Be Offside from a Goal Kick”

Correct. There is no offside offence from:

  • Goal kicks
  • Throw-ins
  • Corner kicks

“You Cannot Be Offside in Your Own Half”

Correct. A player cannot be in an offside position if they are in their own half of the field.

The Second-Last Opponent Rule

Why “second-last” and not “last”? Because the goalkeeper usually counts as one. If the keeper is the last opponent, then the outfield defender becomes the second-last opponent.

But what if the goalkeeper is up for a corner? Then the two outfield players closest to goal become your reference points.

Deliberate Play vs Deflection

This is where it gets tricky. If a defender deliberately plays the ball (not a deflection or save), any prior offside position is reset.

Deliberate play: Defender has time to control the ball, make a decision, passes or clears it - new phase of play begins.

Deflection: Ball bounces off defender unexpectedly - original offside still counts.

Practice Makes Perfect

Understanding the offside rule intellectually is one thing. Making split-second decisions in a match is another. That is where RefereeGPT helps - scenario-based questions that train your decision-making for real match situations.


Want to test your offside knowledge? Try RefereeGPT free - 5 questions daily, no card required.