In the last two minutes of each half, the time on the clock becomes extremely important. There are several rules that come in play, including the potential for a 10-second runoff. The runoff has been in the NFL in since 1955, and its purpose is to nullify the offense’s advantage when the clock stops to adjudicate penalties they have committed. The NFL also added a provision in 2010 that affects plays where there are calls overturned by instant replay.

As of the 2017 season, the 10-second runoff rules apply after the 2-minute warning. (Previously it only applied to the last minute of the half.)

Fouls that cause a run-10

Any foul that is considered to be an illegal act to conserve time are subject to special timing rules. These include:

a foul by either team that prevents the snap, for example: false start encroachment illegal shift (offense not set)

intentional grounding

an illegal forward pass thrown beyond the line of scrimmage

throwing a backward pass out of bounds

spiking or throwing the ball in the field of play after a down has ended, except for a touchdown

illegal substitution, unless obviously not to conserve time

any other intentional foul that stops the clock

If any of these fouls are against the offense, and the clock is not stopped for another reason, a 10-second runoff will apply. The defense has the option to take the yardage for the penalty but decline the runoff, but if they decline the penalty the runoff must also be declined.

Most fouls that would be encountered during the course of regular play are not considered to be illegally time consuming.

Negate runoff with a timeout

The offense also has the opportunity to use a timeout to negate a runoff. If a runoff is applied, 10 seconds are subtracted from the game clock and the clock will start on the referee’s ready-for-play signal. If there are 10 seconds or less to go, the half or game will be over.

The offense gets the option once the defense has accepted to enforce the runoff.

Conserving time on defense

There are never runoffs against the defense, but if the defensive team commits any fouls that intentionally stop the clock (typically, snap-killing fouls), the offense has the option to start the clock on the snap or on the ready-for-play signal and may opt to have the play clock reset to 40 seconds. If there is less than 40 seconds on the clock, the referee can declare the game over.

Excess injury timeout

If the offensive team is granted an excess timeout for an injured player, the defense will have the option to enforce a runoff, unless the clock is stopped for some other reason. An excess timeout is an injury timeout when the team has already used its 3 timeouts. The “fourth” timeout does not have a yardage penalty, but the “fifth” timeout of the half is a 5-yard penalty as well.

If there are injuries by both teams, there is no runoff. All rules as to when timeouts are charged for injuries apply to the excess timeout (for example, an injury caused by a defensive foul is not charged). Any stoppage due to the ATC spotter identifying a player for removal is a “medical timeout” and is not considered a charged timeout.

Replay reversal to a running clock

This section is updated to reflect the procedures in effect beginning in 2018.

Continuing the circumstances following the two-minute warning, a replay reversal can trigger a 10-second runoff. These will invariably be replays that are initiated by the replay official.

When there is a reversal, the clock is reset to the time the ball is declared dead under the reversed ruling, although, at minimum this will be no less time than is already on the clock. After that clock adjustment is made, if the reversed ruling has a running clock, there is a 10-second runoff applied. Neither team can decline the runoff, but either team can use a timeout to prevent the runoff. (Previous to 2018, the runoff only applied if there was reversal that made a stopped clock a running clock.)

If there is no reversal, the game and play clock will continue from where they were at the point of interruption (but no less than 10 seconds on play clock) on the ready-for-play signal.