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?


There is quite a couple of 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 tu 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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