Former One Nation Senator Rod Culleton has been formally disaqualified from holding a senate seat.
In a statement released on Wednesday, Senate President Stephen Parry confirmed there was now a senate vacancy.
"Having received the necessary documentation of the facts from relevant officials, I have informed Senator Culleton and notified the Governor of Western Australia ... that there is a vacancy in the representation of that state as a consequence of the disqualification of Senator Culleton," he said.
Mr Parry said Mr Culleton had been disqualified after being declared an "undischarged bankrupt".
"It is a necessary and automative consequence of the declaration of bankruptcy of a serving senator that his place as a senator becomes vacant," the statement said.
However, Mr Parry said this was not the end of the matter.
"The senate has referred to the Court of Disputed Returns questions about the eligibility of Rod Culleton to have been chosen as a senator," he said.
"It will be necessary for the Court of Disputed Returns to deliver its answers to the referred questions before it will become apparent how the vacancy may be filled.
"The same situation applies to the vacancy in South Australia caused by the resignation of Bob Day whose eligibility to have been chosen as a senator was also the subject of a referral of questions by the senate to the Court of Disputed Returns."
Mr Parry said both matter would be reported to the senate when it meets on February 7.
Mr Culleton has vowed to fight the bankruptcy ruling and has insisted his is not insolvent.
If his disqualification is upheld there will need to be a recount of Western Australian senate votes to see who should take over his seat.
The same process will occur for Mr Day's seat.