What Is an Offside Penalty in Flag Football?

Flag football is different in many ways from tackle football, but it is still based on tackle football. This means it shares many of the same rules as tackle football, and as such, many of the same penalties. One penalty that both sports share much in common is the offside penalty.

The offside penalty in flag football is a minor type of foul that occurs when a defensive player is across the imaginary line of scrimmage into the offensive team’s area at the time the ball is snapped. If this type of foul occurs, the advancing team will receive a five-yard penalty.

A typical offside foul is caused by over-eagerness on the part of the defender; this can be especially tough for younger kids. Let’s take a look at this foul and the penalties from it in more depth.

More Background on the Offside Penalty

The job of a team’s defense is to stop the advance of the team with the ball. In the world of flag football, the defense must prevent the opposing offense from gaining yards, or at least, minimizing the yards they offense gains. Sometimes, the eagerness of the defenders to make the play can lead to the committing of fouls.

An offside penalty in tackle or flag football occurs when a defensive player crosses the line of scrimmage before the snap the ball, and is still there when the ball is snapped. This type of foul typically has the following penalty: five yard penalty against the defending team and the offense repeats the down.

Some flag football leagues may use the term “neutral zone infraction” instead of “offside”, but these are in actuality the same foul with the same penalty.


Some Interesting Aspects of the Offside Foul in Tackle Football

  • Before 1925, if an offside foul occurred, the referee penalized the defense by awarding the offense an automatic first down, plus a five-yard gain for the offensive team. It was after 1925 that the American Football Coaches Association decided to eliminate the automatic first down aspect of the penalty. Only the five-yard advance remained, and it continues to this day.
  • A defender can jump across the line of scrimmage, and if he returns to the defensive side before the snap of the ball, it is not a foul.
  • An offside foul is a foul committed by a team’s defense. When an offensive player moves early (whether across the line of scrimmage or not), the foul is not called offside but a false start.
  • When the defensive player jumps before the snap of the ball and causes the offensive player also to jump, it is a foul for defense.
  • When the defensive player jumps before the snap of the ball and touches the offensive player, it is an encroachment defensive foul.

Understanding the Line of Scrimmage to Better Understand Offside Fouls

The scrimmage line or line of scrimmage is an imaginary line that crosses the field of play from sideline to sideline. No team may cross this line until the play begins. Here are some key points to understand about the line of scrimmage:

  • The location of the line of scrimmage will always be where the referee places the ball.
  • The line of scrimmage will always be parallel to the goal lines.
  • Most people don’t know this, but technically there are always two lines of scrimmage. One line is in front of the offensive team, and the other is in front of the defending team.
  • The space or area between the two lines of scrimmage is called the neutral zone, and it is the width of the football length. Only the offensive center player may have any part of his body in this area.
  • In the NFL, for the play to be legal, at least seven players from the offense must line up at the line of scrimmage. Of those seven players, at least two must be eligible receivers.
  • You may hear sports fans and some commentators refer to the neutral zone as the entire line of scrimmage. The reality is that this statement is incorrect.
  • You may also hear people refer to the line of scrimmage as the defensive line of scrimmage. This statement occurs because of the two lines of scrimmage; the defensive line of scrimmage is the one that measures a team’s progress toward scoring.
  • The most common fouls related to the line of scrimmage are an offside and false start.

Does the Committing of an Offside Foul Always Stop the Play?

When a defender is offside, the referee may or may not allow the play to continue. If the referee deems that the defender is caught just across the line of scrimmage but is not in a position that gives the defense and unfair advantage, the referee will likely not blow the whistle and stop the play, but will instead allow the play to continue and then announce the foul at the end of the play. In this situation, the offensive team can elect to take the result of the play, or accept the penalty against the defense. If the defensive player is far across the line, in such a way that the referee feels like the defense has an advantage, then the referee will likely blow the whistle and stop the play, enforcing the penalty at that point.

What Is a False Start, and How Does It Differ From Offside?

The false start is a foul committed by the offense. All offensive players (unless one is in legal motion pre-snap) must be stationary when lined up pre-snap. When an offensive player moves before the snap, the referee will penalize the offensive team with a false start. The false start typically carries a 5-yard penalty and a loss of the down. The foul exists because the early movement gives an advantage to the offense by putting the offensive player in a privileged position.

What Is the Primary Difference Between a False Start Foul and an Offside Foul?

Now that we know what the offside and false start fouls are, let’s look at the difference between both infractions. Some people use both terms interchangeably to refer to the same type of foul which contributes to the confusion. The key differences between false start and offside is:

  • A false start is a foul that applies only to offense. It is when an offensive player moves before the snap of the ball.
  • Offside is when a player is caught across their line of scrimmage when the ball is snapped. They may or may not be moving (for example, they could have lined up across the line). Offside can technically be called on either the defense or the offense, but it is almost never committed by the offense.

A Final Thought on the Offside Foul in Flag Football


Offside is one of the most common minor fouls in flag football. It is one that coaches need to work on with their young players to help them learn where to line up, and to stay still until the ball is snapped. It can be demoralizing to your team to allow a silly mistake to give the other team an advantage or help them move down the field.

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Kyle Albert

Kyle Albert is a father, software engineer, and youth flag football coach. He has coached flag football teams ranging from 2nd grade all the way to high school. He lives with his family in Northern Virginia.

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