The Scottish Premier League has set a deadline for Rangers to hand over key documents relating to an investigation into possible dual contracts.
A request was made by the SPL in March and BBC Scotland has learned they are still awaiting information from the club's administrator Duff & Phelps.
If the club fail to comply, it is understood the league will look to impose some form of sanction.
The investigation concerns Rangers' use of employee benefits trusts.
The EBTs are the subject of a long-running HM Revenue and Customs tax tribunal, which could result in a £75m bill for Rangers.
A BBC documentary, 'Rangers - Who Sold the Jerseys' - revealed that over 70 players and coaches benefited from the scheme.
Meanwhile, Scottish FA chief executive Stewart Regan says his organisation has no plans to step in to investigate possible dual contracts at Rangers, insisting he will leave it to the SPL.
The SFA will act as the appeal body should one be needed after the SPL investigation.