Offside has a reputation for being football's most confusing rule. It really isn't — once you know there are two things that must both be true at the same moment, the rest falls into place. Here it is in plain English, with the myths cleared up.
The simple version
A player is caught offside when, at the instant a team-mate plays the ball to them, both of these are true:
- they are in the opponents' half of the pitch, and
- they are closer to the goal line than both the ball and the second-last defender (in practice, the last outfield defender, since the goalkeeper is usually the very last).
If both are true, and they then get involved in the play, the referee's assistant raises the flag and the attack is stopped. That's the whole core of it. The rule exists to stop attackers simply loitering next to the goal waiting for a pass — it forces them to time their runs.
The key word: "when the ball is played"
This is where people get confused. Offside is judged at the exact moment the ball is passed, not when the attacker receives it. So a striker can be level with the defenders, then sprint past them the instant the pass is struck and be perfectly onside — because they were level at the moment that matters. That's why you'll see a player collect the ball miles beyond the defence and still not be offside: they timed their run with the pass. It looks wrong; it's right.
When you can NOT be offside
There are a few situations where offside simply doesn't apply, no matter where you're standing:
- In your own half of the pitch.
- If you're level with the last defender (or the ball) — level is onside.
- Receiving the ball directly from a throw-in, a corner, or a goal kick.
"Interfering with play" — the subtle part
Standing in an offside position is not, by itself, an offence. You're only penalised if you become involved — by touching the ball, by challenging an opponent for it, or by clearly blocking the goalkeeper's view or movement. That's why an attacker can stand in an offside spot and not be flagged, as long as they leave the ball alone and don't affect a defender. It's also the source of plenty of arguments, because "did he interfere?" can be a genuine judgement call.
Two myths to drop
- "He was offside because he was past the defender." Only if he was past them when the ball was played — and only if he then got involved.
- "You can be offside from a throw-in." You can't. Throw-ins, corners and goal kicks are all exempt.
Why it feels harder than it is
Modern offside calls are often a matter of centimetres, decided in slow motion with the help of VAR — which is why a goal can be ruled out for an armpit or a toe. The principle, though, hasn't changed: be onside the instant the pass is played, and time your run. Watch a few attacks with the "two things, at the moment of the pass" test in mind and you'll find you're calling them before the flag goes up.
Unofficial fan guide. Not affiliated with FIFA. Based on the IFAB Laws of the Game.