The three-man independent commission, chaired by Lord Nimmo Smith, heard evidence and submissions into alleged undisclosed payments between 2000 and 2011.
A decision will be issued in due course and if found guilty of wrongdoing by the panel, appointed by the Scottish Premier League, Rangers could be stripped of titles won during that period.
The probe was launched before the original Rangers company was consigned to liquidation and the newco club, which now play in the Scottish third division, have refused to recognise or be part of the investigation.
In a statement, the SPL said: "The Independent Commission... to determine issues concerning EBT payments and arrangements at RFC 2012 PLC (in liquidation) (formerly The Rangers Football Club Plc) and Rangers Football Club, heard evidence and submissions at a hearing on 29, 30 and 31 January 2013.
"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 has since launched an appeal against the verdict.