A countdown clock will be used when players are kicking for goal inside 50m during 2016 after a positive trial in the NAB Challenge.

Players have 30 seconds to begin walking in to take their set shot kick for goal, with spectators, players and umpires now able to watch time running down on the scoreboard.

AFL Umpires' boss Wayne Campbell said the introduction of the countdown clock would help umpires remain consistent when applying the time limit as players lined up for goal.

"The feedback from our umpires was that the countdown clock helped assure them they were consistent with the 30 seconds provided to players when kicking for goal," Campbell said.

A match official will activate the 30-second countdown clock when players have a set shot from inside 50.

At this stage, the innovation is set to go at the MCG, Etihad Stadium, Adelaide Oval, Metricon and Domain Stadiums, with the AFL working to overcome any impediments to making it possible at all AFL venues.

The countdown clock is the second innovation to be introduced after the AFL confirmed it would also increase the protected area around the mark to 10 metres this year.