Offside VAR explained: How does it work in the Premier League?

Offside VAR decisions in the Premier League have become the single most discussed officiating issue in the modern game. The technology itself is straightforward: semi-automated offside technology (SAOT) tracks skeletal data points from 12 cameras to draw virtual lines in under 30 seconds. What makes it feel slow is not the system but the human check that runs before it.

Since its introduction in the 2019/20 season, the Premier League has refined how it applies offside VAR. The core principle has not changed: any part of the attacking player that can legally score (head, body, feet) must be behind or level with the second-to-last defender (usually the last outfield player). The goalkeeper counts as one defender, so the defender nearest the goal line is the reference point.

How it works

The Premier League uses an optical tracking system, not a chip in the ball. Twelve cameras mounted under the stadium roof capture 29 data points per player, 50 times per second. When a goal is scored or a potential offside happens, the system identifies the precise moment the ball is played by the passer. That frame is frozen.

From that frame, the system generates three-dimensional lines:

• A blue line for the second-to-last defender (aligned with the foot, torso, or head closest to the goal).
• A red line for the attacking player.
• Green lines indicate the lines are being drawn; yellow means the data is still calculating.

If the red line overlaps the blue line, the player is onside. If any gap exists between them, the player is offside. The system then produces a 3D animation that broadcasters show to explain the call.

Wait times of 60 to 90 seconds happen because the VAR must confirm the attack phase, check for any defensive touch that resets offside, and verify that the correct player passed the ball. The SAOT calculation takes around 15 to 20 seconds. The rest is human review.

Key details

Semi-automated vs. fully automated. Semi-automated means the system draws the lines and identifies the kick point, but a human VAR must still validate the result. Fully automated would remove the human step entirely. The Premier League chose semi-automated to retain referee authority and to allow for pitch-level judgment calls like ball deflection.

What counts as offside. The attacker must be in the opponent's half and nearer the goal line than both the second-to-last defender and the ball. Players level with the second-to-last defender are onside. The hands and arms of an attacker do not count. Only body parts that can legally score are used in the line drawing.

Delay causes. Three common reasons for a long VAR check:

1. The broadcast angle may not align with the exact moment of the pass. The system retimes the frame against multiple camera feeds.
2. A defender blocking the camera view of the attacker's foot can force the system to use a secondary data point.
3. The VAR may check for a potential phase-of-play foul before the goal, which is a separate review not related to the offside check itself.

Goal-line technology is a separate system. Seven cameras track the ball's position relative to the goal line, sending a signal to the referee's watch within one second if the whole ball crosses it. It does not interact with offside VAR.

Common confusions

Why does offside take so long if it is automated? This is the biggest misunderstanding among fans. The automated line calculation is fast. The delay comes from the VAR's need to review the build-up to every goal for potential fouls, handballs, or other infringements before confirming the goal. Offside checks cannot be separated from the wider review process.

What happens if the ball touches a defender before reaching the attacker? If a defender deliberately plays the ball, offside is reset for that phase. Deflections off a defender do not reset offside. Only a deliberate, controlled touch counts. That distinction often causes controversy because intent is subjective.

Can a player be offside from a goal kick, throw-in, or corner? No. A player cannot be offside directly from a goal kick or throw-in. Corners fall under the same rule: no offside from a corner kick. Once the ball is touched by any other player, normal offside rules apply.

Does VAR check every offside or only those related to goals? VAR only reviews offside in the attacking phase of a goal (including missed penalties or direct red card incidents). Offside calls in open play, such as a player receiving the ball while offside in midfield, are left to the assistant referee. VAR does not review every offside flag.

Key takeaways

1. Semi-automated offside technology processes the offside line in 15 to 20 seconds; the remaining delay is human review of the attack phase.
2. The system uses 12 cameras tracking 29 skeletal data points per player, not a ball chip.
3. Deflections off a defender do not reset offside; only deliberate plays do.
4. Players are not offside from goal kicks, throw-ins, or corners.
5. VAR reviews offside only in goal-scoring phases, not every offside flag during open play.

FAQ

Can VAR check offside after a goal is scored? Yes. VAR reviews every goal to confirm the attacking player was onside at the moment the pass was made. The check happens after the goal is scored but before the referee restarts play. If the referee has already restarted, the goal stands.

Why does the Premier League not use the same offside system as the World Cup? The Premier League uses the same semi-automated technology from the same supplier (Genius Sports) that operated at the 2022 World Cup. The visual output and review process are nearly identical.

How does offside work for the goalkeeper? The goalkeeper counts as one of the two outfield players nearest the goal line for offside purposes. If the goalkeeper is outside the box, the reference point becomes the last outfield defender.

Can a player be offside in their own half? No. A player must be in the opponent's half when the ball is played to be penalised for offside.

Internal links

• Read more about Premier League club squad rules and how the 25-player homegrown limit works.
• See which players have been most affected by tight offside calls this season.
• Understanding the FA Premier League history helps explain why the rules continue to evolve.