How and when do I flag for offside?

Q: How and when do I flag for offside?

From the IFAB practical guidelines (2026/27): Raise the flag using your right hand (better line of vision). If the referee stops play, use the flag to indicate the area of the field where the offence happened. If the referee doesn't see the flag straight away, keep it up until it is acknowledged or the defending team clearly has control of the ball. Timing: a player in an offside position is only penalised once they become involved in active play. For example, when an attacker in an offside position who isn't interfering with an opponent touches the ball, that is when you raise the flag. If they don't touch the ball and don't interfere with an opponent, there's no offence and you keep the flag down. Your positioning matters most: stay in line with the second-last defender, or the ball if it is nearer the goal line, and face the field.

Question

Accepted Answer

From the IFAB practical guidelines (2026/27):

Raise the flag using your right hand (better line of vision).
If the referee stops play, use the flag to indicate the area of the field where the offence happened.
If the referee doesn't see the flag straight away, keep it up until it is acknowledged or the defending team clearly has control of the ball.

Timing: a player in an offside position is only penalised once they become involved in active play. For example, when an attacker in an offside position who isn't interfering with an opponent touches the ball, that is when you raise the flag. If they don't touch the ball and don't interfere with an opponent, there's no offence and you keep the flag down.

Your positioning matters most: stay in line with the second-last defender, or the ball if it is nearer the goal line, and face the field.