The three-man panel, chaired by Lord Nimmo Smith, heard evidence and submissions over three days this week into alleged undisclosed payments made to players at Ibrox from 2000 to 2011.
If found guilty of wrongdoing by the Scottish Premier League appointed-commission, Rangers could face the ultimate sanction of being stripped of titles.
The probe was launched before the original Rangers company was consigned to liquidation and the newco club have refused to recognise or co-operate with the investigation.
A statement released by the SPL on Thursday read: "The Independent Commission chaired by Rt Hon Lord Nimmo Smith, sitting with Nicholas Stewart QC and Charles Flint QC, to determine issues concerning EBT payments and arrangements at RFC 2012 PLC (in liquidation) (formerly The Rangers Football Club Plc) ("Oldco") and Rangers Football Club, heard evidence and submissions at a hearing on 29, 30 & 31 January 2013.
"Parties before the commission were: The Scottish Premier League Limited, represented by Mr Rod McKenzie of Harper MacLeod; and Oldco, represented by Mr James Mure QC, instructed by Mr Michael McLaughlin of DWF Biggart Baillie.
"Mr Mure QC also on 31 January represented Rangers Football Club and The Rangers Football Club Ltd ("Newco") in regard to submissions on any possible sanction which might apply in the event that any breach was established.
"The Commission has reserved judgement and will issue a full written decision in due course.
"Until that decision is issued no further comment will be made."
The payments centre on financial arrangements made by the Employee Benefit Trust scheme run by former Rangers owner Sir David Murray's company. Murray International Holdings won its appeal in principle against a tax bill surrounding the EBTs, with most of the payments deemed to be loans. Her Majesty's Revenue and Customs launched an appeal against the verdict.