When should I flag for a foul the referee hasn't seen?

Q: When should I flag for a foul the referee hasn't seen?

From the IFAB practical guidelines (2026/27): When to flag: raise the flag when a foul or misconduct is committed in your immediate vicinity or out of the referee's vision. In all other situations, wait, and give your opinion if asked. Before flagging, be sure that: the offence was out of the referee's view, or the referee's view was obstructed, and the referee would not have played advantage. Use the "wait and see" technique: don't flag if the fouled team benefits from advantage. Eye contact with the referee is essential. How to flag: Raise the flag with the hand you'll use for the rest of the signal, which shows which team gets the free kick. Make eye contact with the referee. Give the flag a slight wave back and forth, avoiding excessive or aggressive movement. Near the penalty area: Defender's foul inside the area the referee hasn't acted on: flag, use the beep signal if you have one, then visibly move down the touchline towards the corner flag. Foul just outside the area: make eye contact, flag if necessary, and make a clear movement along the touchline towards the halfway line to show it was outside.

Question

Accepted Answer

From the IFAB practical guidelines (2026/27):

When to flag: raise the flag when a foul or misconduct is committed in your immediate vicinity or out of the referee's vision. In all other situations, wait, and give your opinion if asked. Before flagging, be sure that:

the offence was out of the referee's view, or the referee's view was obstructed, and
the referee would not have played advantage.

Use the "wait and see" technique: don't flag if the fouled team benefits from advantage. Eye contact with the referee is essential.

How to flag:

Raise the flag with the hand you'll use for the rest of the signal, which shows which team gets the free kick.
Make eye contact with the referee.
Give the flag a slight wave back and forth, avoiding excessive or aggressive movement.

Near the penalty area:

Defender's foul inside the area the referee hasn't acted on: flag, use the beep signal if you have one, then visibly move down the touchline towards the corner flag.
Foul just outside the area: make eye contact, flag if necessary, and make a clear movement along the touchline towards the halfway line to show it was outside.