Under the new rules, the formal nominations for leader of the Labor Party will be open a week from today.
A ballot will be held by the caucus and grassroots members if more than one leadership candidate emerges.
Eligible candidates for the leadership need 20 percent support from the caucus.
The vote for leader is split 50-50 between caucus and grassroots members, giving the 44,000 rank and file supporters a say for the first time in the party's history.
It is still unclear whether the party will use a postal vote or a secure online voting method for the ballot among the rank-and-file party members.
The new caucus rules state that all ballots must be received 27 days after the call for nominations.
Counting will take place three days later.
The rules were endorsed at a special caucus meeting on July 22, called by the then leader of the Labor Party, Kevin Rudd.
"Each of our members gets to have a say, a real say, in the future leadership of our party," Mr Rudd said at the time. "Decisions can no longer simply be made by a factional few."
The proposal was seen as a measure to prevent multiple leadership challenges.
A ballot can only be called if the prime minister resigned or requested one, or if at least 75 per cent of caucus signed a petition stating the leader had brought the party into disrepute.
In opposition, a ballot would be held automatically after each federal election or if at least 60 per cent of caucus signed a petition.
