The CFMMEU could lose tens of thousands of members if the Federal Court approves a long-running bid by mining workers seeking to split off and form their own union.
Since a vote approving the withdrawal in March 2021, the Mining & Energy Union has wanted to separate from Australia's largest trade union organisation, the Construction, Forestry, Maritime, Mining and Energy Union.
On Wednesday, the MEU filed an application with the Federal Court seeking to formalise the withdrawal and create another union for its 20,000 members.
The court will be asked to allocate enough assets to the MEU and to set down December 1 as the formal date of the split.
"We are confident this is the final step in what has been a lengthy process to deliver on our members' wishes to withdraw from the CFMMEU," said MEU general president Tony Maher.
"We appreciate members' patience as we've worked through considerable legal and logistical complexities to reach this point.
"Our union has a long and proud history and our members have expressed the strong view that our next chapter should be as a standalone union fully committed to representing the interests of mining and energy workers."
If the demerger is approved, the CFMMEU will lose one M in its name, being known instead as the Construction Forestry Maritime Employees Union, or CFMEU.
A court date has yet to be set.
The mega-union, which represents around 150,000 workers according to its website, did not respond to a request for comment.
