Throughout many NFL games, there is almost always one pre-snap call, and many of those are on the offense for a small flinch. During all of the games that I have watched, I see refs calling out mostly different penalties that are related to the false start. What are the key differences between these three penalties, encroachment, neutral zone infraction and offside?

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There are quite a few fouls that can happen at the start of a down:

  • False Start: Movement of an offensive player prior to the snap, e.g. a lineman changing their stance or a receiver moving forward.
  • Encroachment: Movement of defensive player into the neutral zone prior to the snap who then touches an opponent or the ball.
  • Neutral Zone Infraction: Movement of defensive player into the neutral zone prior to the snap who causes the reaction of an opponent in close proximity.
  • Offside: Player lined up in the neutral zone, can be caused by both offense and defense.
  • Illegal Motion: One offensive player in the backfield is allowed to move parallel or backwards, all others have to be set for at least a second, if any of this is violated it's an illegal motion.
  • Illegal Formation: Offense must have 7 players at the line, eligible receivers left and right to their linemen and not between linemen. Failing to do so is an illegal formation.
  • 12 Men On The Field: You are only allowed to have 11 men on the field, with the ruling being a bit more strict for offense, including the huddle.
  • Delay Of Game: If the offense fails to put the ball in play before the play clock runs out.

All of these fouls will cause a 5 yard penalty, but no automatic first down (in case of a defensive foul).

You can read more about this in the rules sections 7.4 (action at or before the snap), 5.1/2 (players and substitutions), 3.19/20 (scrimmage line, neutral zone, offside).


A defender crosses the Line of Scrimmage before the snap (without touching an opponent).

Offside, but with touching an opponent.

Neutral zone infraction:
This is basically the same rule as offside, but will usually be called when a defender causes an offense player to false start by committing an offside foul or a defender already lines up illegally (e.g. head sticking out).

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