Duff & Phelps indicated in a document circulated yesterday that no money will be paid under a proposed Company Voluntary Arrangement (CVA) before the conclusion of two legal cases and the "big tax" case involving HM Revenue & Customs (HMRC).
The tax case relates to Rangers' use of controversial Employee Benefit Trusts (EBTs) for staff and could mean a bill of £75 million.
Duff & Phelps is also suing Collyer Bristow, the law firm involved in former owner Craig Whyte's takeover, and Whyte's Rangers FC Group for £25m.
The latter case is not due to be heard until October, and any appeal could lead to further delays.
It means the 332 creditors will have to vote to accept the CVA at a creditors' meeting on June 14, not knowing how much they will receive.
Experts described the move as unusual, with one admitting it will be difficult "to get over the line".
Donald McNaught, director of business recovery and insolvency in Glasgow for Johnston Carmichael, said: "What you would typically expect would be a proposal which has a higher degree of certainty attached to it. Here, there are an awful lot of variables which will make it challenging to get over the line.
"Creditors want to have some degree of certainty they will get a certain number of pence in the pound."
Alongside the £8.5m being loaned by former Sheffield United chief executive Charles Green's consortium, up to £2m more could be available at the moment through transfer money Rangers are owed.
But less than £5m of that £10.5m could be left once professional services fees, including those of Duff & Phelps, and expenses have been paid.
The most optimistic scenario would see a creditors' pot of about £25m and no liability from the tax case, leaving them with around 40p for each pound of debt. But the loss of the tax case could leave just a few pence per pound.
The secured creditors include Sir David Murray's Premier Property Group (PPG), finance company Close Leasing, The Scottish Sports Council and Rangers FC Group.
Close Leasing is due £1.56m in relation to a deal that provided finance in exchange for future income from catering, while The Scottish Sports Council is owed more than £500,000 in relation to a security it holds over the Murray Park training ground.
Paul Clark, joint administrator, said: "We're dealing with something where we don't know what the final distribution [of money] will be. What we do know is that it will be a better solution than any other outcome."
Should the CVA fail, the sale of Rangers Football Club plc and its assets to a new company would appear to be the only way forward. Mr Green has already agreed a £5.5m purchase price for this eventuality.
The main creditor, Ticketus, which is owed around £27m by the club for advanced season ticket sales, said its obligation was to achieve the best deal for its investors.
A spokesman could not confirm whether it would back the CVA proposals.
It is believed that it will take what it can from Mr Green's offer as the company mounts a civil action against Whyte to retrieve its money.
A spokesman said: "It's not for us to talk about Rangers Football Club. It is for us to have a duty to investors."
HMRC, which is currently owed more than £21m by Rangers, would not comment on whether it backs the proposals.
Other creditors were equally tight-lipped when contacted by The Herald. They range from hotels to media services to football clubs, including Hearts, who are owed £800,000.
Andy Kerr, president of the Rangers Supporters Assembly, advised debenture holders not to join the CVA.
Supporters raised more than £7.7m to build the deck on the Govan stand after the club released 6050 debentures for sale in 1990 for between £1000 and £1650.
Mr Kerr said: "These people are all very loyal fans of the club, and I would appeal that the best thing for them to do is not to exercise their right to vote, as the agreement will essentially be down to Ticketus and HMRC."
l Newsquest (Herald & Times Ltd) is a creditor and owed £1500.