How does semi-automated offside technology work in the Bundesliga?
VAR officials in the Bundesliga and Bundesliga 2 have additional help in determining offside decisions thanks to semi-automated offside technology. How does it work?
Previously, since the introduction of VAR, any offside decisions that have been subject to review have been made by technical operators manually drawing the corresponding lines on the attacker and the last defender at the moment the ball was played.
This obviously takes time in order to ensure accuracy and correct decisions being made.
That process has now been streamlined with the help of semi-automated offside technology (SAOT), which has been installed at the Kölner Keller (the Cologne Cellar), as the VAR headquarters in Germany are colloquially known.
Watch: How does SAOT work in practice?
There are 11 additional cameras installed under the stadium roof that track the players and the ball. They register 21 offside-relevant body parts of every player (i.e. not arms and hands).
When a goal is scored or for a potential penalty, the VAR checks for a potential offside in the build-up. If the SAOT recognises a potential offside, it registers a so-called 'event'.
The video assistant referees can then examine the still shots of the potential offside from different angles.
The system creates red lines and crosses for the attacker's body part closest to the goal and blue for the defender.
The job of the referees is then to check and verify the plausibility of the system's results. That means:
- Have the correct attacker and defender been selected?
- Has the system drawn lines on an attacker in an offside position but not interfering with play?
- Has the correct moment been selected, from when the ball is played? The system allows quick selection of three frames before or after
- Have the lines been drawn correctly from the relevant body parts on the attacker and defender?
Only when all aspects have been verified will the VAR confirm the event. And only then is the animation seen on TV created.
The VAR does not see the images as an animation, but as the familiar lines drawn on the screen - only these are not drawn manually but by the SAOT.
In these scenarios, the VAR - i.e. the human element in the process - is only in charge of checking the plausibility and finally confirming the outcome.
In the event that the SAOT does not work as required, then the VAR is still able to create the lines manually, as they have done since video assistants were introduced.
Watch: The introduction of referees announcing VAR decisions during matches in January 2025
“The technology provides us with the result as to whether or not there is a potential offside situation,” said Robert Schröder, who has officiated more than 80 top-flight matches in Germany since becoming a Bundesliga referee in 2018, and is now also a FIFA-recognised video assistant referee.
“It also provides us with the lines that we used to create manually in the past, which took a lot of time. The system also provides us with the playback time. The animation [shown on television] is only a visual representation of the result, which we determined beforehand in the check.”
Get more on the rules and regulations of football here
Related news
Who are Bundesliga 2's oldest ever goalscorers?
After netting on his Bundesliga 2 debut for Schalke, Edin Džeko etched his name into the German second division's history books.
Bundesliga transfer centre: January 2026
A handy overview of all the confirmed deals in Germany's top flight this winter...
Kane in contract extension talks
Bayern have confirmed they are talking to Harry Kane about a new deal with the club.