Jackie Trad has been referred to the state parliament's ethics committee over the purchase of an investment property at Woolloongabba, along the route of the state government's Cross River Rail project which she was overseeing at the time.

The issue is expected to dominate debate as politicians come together for next week's final sitting of parliament.

Queensland's Crime and Corruption Commission in September cleared Ms Trad over the purchase of the property.

But parliamentary speaker Curtis Pitt confirmed that the purchase would be referred to the ethics committee over issues raised by the CCC investigation.

"I have reached the conclusion that there are sufficient questions of fact to be determined against the evidence such that it would be prudent to refer the matters to the Ethics Committee for further consideration," Mr Pitt said in documents tabled on Friday.

"I also wish to stress that I have not taken this decision lightly, and I have given this decision lengthy and serious consideration."

The deputy premier has promised to cooperate fully with the ethics committee investigation.

"The CCC found there was no evidence of corrupt or dishonest conduct in the Deputy Premier's late lodgement of paperwork relating to the purchase of a property," a spokesman for Ms Trad told AAP.

"As the matter is now before the ethics committee, it would be inappropriate to comment further."

Australian Associated Press