Offside rule in football explained: Law 11 made simple

A football player is offside only when two things are true: they were in an offside position at the moment a teammate played or touched the ball, and they then became involved in play. Standing in the wrong place is not, by itself, an offence.

The rule is Law 11 of the Laws of the Game, written by the International Football Association Board (IFAB). Its wording did not change for the 2026/27 season, which began on 1 July 2026, but the technology used to apply it keeps changing, and so do the arguments about it.

Quick answer: You are in an offside position if any part of your head, body or feet is in the opponents’ half and closer to their goal line than both the ball and the second-last opponent. It only becomes an offence if you then play the ball, interfere with an opponent, or gain an advantage. Level counts as onside, and there is no offside from a goal kick, throw-in or corner kick.

What counts as an offside position?

Law 11.1 sets three conditions, and all three must be met when a teammate plays or touches the ball. The player must be in the opponents’ half (the halfway line itself does not count). Some part of their head, body or feet must be nearer the opponents’ goal line than the ball. And that part must also be nearer the goal line than the second-last opponent.

Hands and arms are ignored, for attackers, defenders and goalkeepers alike. The IFAB draws the line precisely: the upper boundary of the arm is level with the bottom of the armpit, so a shoulder can put a player offside but a hand cannot.

The “second-last opponent” is usually the last outfield defender, because the goalkeeper is normally the last. If the goalkeeper has come out, two outfield players can be the last two, and the attacker is measured against the second of them. A player level with the second-last opponent, or with the last two opponents, is onside.

When does an offside position become an offence?

Law 11.2 lists three ways a player in an offside position becomes guilty:

1. Interfering with play by playing or touching a ball passed or touched by a teammate.
2. Interfering with an opponent, for example by blocking the goalkeeper’s line of vision, challenging for the ball, or making an obvious action that affects an opponent’s ability to play it.
3. Gaining an advantage by playing a ball that rebounds or deflects to them off the goalpost, the crossbar, a match official or an opponent, including a ball an opponent has deliberately saved.

The punishment is an indirect free kick to the defending team, taken from where the offence happened, even if that is in the attacker’s own half.

Why a defender’s touch can make an offside player onside

This is the part of Law 11 that causes most rows. If an opponent deliberately plays the ball, the attacker’s earlier offside position stops counting. A deflection or a save does not reset anything.

The case that forced a rethink came in the UEFA Nations League final in October 2021. Kylian Mbappé was in an offside position when Theo Hernández passed, but Spain’s Eric García stretched a leg toward the ball, the referee Anthony Taylor judged that a deliberate play, and Mbappé’s winning goal stood in France’s 2-1 win. UEFA’s refereeing chief Roberto Rosetti said the decision was correct under the law as written, while arguing that the interpretation clashed with the spirit of the law.

The IFAB’s text now spells out what “deliberate play” means: the player had control of the ball with a realistic chance of passing it, keeping it or clearing it. Its guidance lists signs that a touch was deliberate, such as the ball travelling from a distance, the player having a clear view of it, a slow or predictable ball, and time to get the body in position. A desperate stretch at a fast ball is closer to a deflection, which would leave the attacker offside.

When can’t a player be offside?

A player cannot be penalized for offside if they receive the ball directly from a goal kick, a throw-in or a corner kick. They also cannot be offside while in their own half, when level with the second-last opponent, or when behind the ball.

Two less familiar rules close loopholes. A defender who steps off the pitch without permission still counts as standing on the goal line or touchline until the next stoppage, so leaving the field cannot be used to play an attacker offside. An attacker who walks off to show they are not involved, then comes back and joins in, is treated as being on the goal line.

How semi-automated offside technology works

The 2026/27 law changes did not touch Law 11. Under a change to Law 5, the IFAB now explicitly allows competitions to use technology for offside decisions, including semi-automated offside technology (SAOT). It is an option for each competition, not a requirement.

The Premier League switched SAOT on from 12 April 2025. According to the league, up to 30 cameras around each stadium track the ball and up to 10,000 surface points on each player, with several cameras recording at 100 frames per second. The system suggests the “kick point”, the frame in which the pass was played, and draws the offside lines automatically. The video assistant referee still has to confirm that the kick point and the body parts are right. The league expected the change to save about 30 seconds on a close call; it did not claim it would make decisions more accurate.

That caveat matters. At 100 frames per second, a player running at 8 meters per second moves 8 centimeters between two frames. A “millimeter” offside line is drawn on a picture that is already a choice between two moments.

Why assistant referees get offside wrong

Before video, the judgment belonged to the assistant referee alone, and scientists found it was harder than it looks.

In 2000, a team led by Raôul Oudejans at Vrije Universiteit Amsterdam published a study in Nature in which three professional assistant referees judged 200 staged offside situations and made 40 errors. The researchers blamed viewing angle: an assistant standing slightly beyond the last defender sees the attacker and defender projected at a misleading angle.

A 2006 study in the Journal of Sports Sciences by Werner Helsen and colleagues looked at 337 offside situations from the 2002 World Cup and put the error rate at 26.2 percent. Most mistakes, 86.6 percent, were flags raised when the attacker was actually onside, and errors were most common in the first 15 minutes. Helsen’s team argued the main cause was the “flash-lag effect”, a quirk of perception in which a moving object seems further ahead than it is. The two groups disputed each other’s explanations in the same journal, but both found that the human eye is badly suited to this exact task.

Would “daylight” offside settle the arguments?

Arsène Wenger, FIFA’s chief of global football development, has long argued for a different line. Under the “daylight” rule, an attacker is onside if any part of the body they can legally score with is level with or behind the second-last defender, and offside only when there is a clear gap.

FIFA began a trial in the Canadian Premier League on 4 April 2026, with the IFAB’s approval. Inside World Football reported in late April that the biggest early change was at set pieces, where non-penalty goals rose to 0.73 a game over the first 11 matches, from 0.54 the season before. No final findings had been published by late October 2026.

The daylight rule would favour attackers, but it would not end marginal calls. The line would still exist; it would simply move to the attacker’s trailing heel or knee, and VAR would still have to decide whether a few centimeters of gap is “daylight”.

The law has been rewritten many times before

• 1863: The Football Association’s first laws make any attacker ahead of the ball offside.
• 1866: A player becomes onside with three opponents between him and the goal.
• 1925: The number drops to two. Football League goals rise from 4,700 in 1924/25 to 6,373 the next season from the same number of games.
• 1990: A player level with the second-last defender is made onside.
• 2005: Only body parts a player can legally score with count when judging position.
• 2026: The Canadian Premier League begins FIFA’s daylight trial.

What to check the next time VAR rules on offside

1. Find the kick point: offside is judged when the teammate plays the ball, not when the attacker receives it.
2. Ignore the arms: only the head, body and feet count, with the armpit as the boundary.
3. Ask who touched it last: a deliberate play by a defender resets offside; a deflection or a save does not.
4. Check involvement: an offside player who never touches the ball or affects an opponent has done nothing wrong.

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