The Toffees number one attacking midfielder, who scored his 100th goal in English football on the weekend, could be called up by the Socceroos in December ahead of the Asian Cup which kicks off in Qatar in early January.
Everton boss David Moyes admitted Cahill's likely absence wouldn't be ideal but said the club afforded the same luxuries to African players at the beginning of this year for the African Cup of Nations.
"We could lose Tim to that in a similar way we lost Joseph Yobo and that to the African Nations so that's a big issue," Moyes told the Daily Post.
"He could be called up in the middle of December and they've got that competition all through January."
Australia take on South Korea, Bahrain and Iran in their group of the 2011 Asian Cup.