Siren rules, the interchange, team sheets, footballs, and what happens when a game can't finish.
What counts as a legal ball, when the siren ends a quarter, how many players can be on the interchange, and what happens when a match can't be completed. The on-field stuff most fans think about — codified in detail.
Every AFL premiership match is played with a Sherrin football, the only approved ball under Regulation 9.1. The home club supplies and selects the match-day football, subject to inspection by the field umpires before play begins.
Adverse conditions — heavy rain, unusual venue factors — can trigger the use of additional or replacement footballs at umpire discretion (Regulation 9.3).
An AFL match is played in four quarters of 20 minutes of actual playing time plus time-on. Time-on is added for stoppages, scores, and other delays — which is why quarters typically run 28 to 32 minutes of real time. The siren ends the quarter, not the game clock: Regulation 10.4 is clear that the quarter ends when the siren sounds, regardless of what's happening on the field.
If a player is in the act of kicking when the siren sounds, the kick plays out: a goal scored after the siren counts, provided the player was in legitimate possession before the siren. This rule has produced some of the competition's most celebrated moments — most famously Matthew Lloyd's 2001 Preliminary Final set shot and the after-the-siren winners that define September.
Each club submits an Official Team Sheet before every match (Regulation 12). The sheet lists 22 players — 18 on the field plus four on the interchange bench — along with nominated emergencies. Any changes after submission are tightly regulated.
The current interchange system allows four players on the bench with unlimited rotations during the match, subject to a cap. The medical substitute rule, in place since 2021, adds one additional player who can be activated only once per match to replace a genuinely injured teammate. Once the sub is used, that player is in for the rest of the game and the replaced player cannot return.
Regulation 12.5 formalises the Head Injury Assessment protocol. A player who has sustained a suspected concussion must be removed from the field for medical evaluation and cannot return until cleared. The AFL mandates a minimum 12-day stand-down for any player diagnosed with a concussion — a significant change from earlier eras when players routinely returned to the field after head knocks.
If a match cannot start on time (Regulation 32) or cannot be completed (Regulation 33), the AFL Commission has discretion over how to proceed. Options include delaying the start, playing shortened quarters, rescheduling to a later date, or — in extreme cases — awarding the points to one club or declaring a forfeit.
Forfeitures are rare but possible. Under Regulation 32, a club that refuses or fails to take the field is deemed to have forfeited, with the opposition awarded the four premiership points. An abandoned match may be declared complete if played past three-quarter time, or rescheduled if abandoned earlier.