The union, which comprises six supporters organisations, is urging over 35,000 of their fellow fans NOT to renew their season tickets this summer.
The umbrella group has called on the club board to give Gers supporters security over both Ibrox and Murray Park in return for their cash.
A company that has former director Dave King and ex-captain Richard Gough as directors has been set up to hold the security if it is granted.
Rangers chairman David Somers last month warned that withholding season ticket money could risk the Ibrox club being unable to "continue as a going concern".
But a strongly-worded Union statement read: "We have been making steady progress on the set-up required for the season ticket fund.
"We understand the frustration of fans who wish to contribute, but we would ask them to understand that we must ensure it is set up properly, legally and with total transparency.
"We thank them for their patience and can assure them that an alternative to placing blind faith in this board will be in place shortly.
"We will have a website in place within the next 10 days, ahead of the May 6 deadline, where fans can register their details and securely place their season ticket money.
"This money will only be passed to the club in return for season tickets if security is granted over Ibrox and Auchenhowie. Those are our only conditions.
"If that security is not granted then fans will retain their money and can decide themselves how to proceed at the start of the new season."
Meanwhile, the Union has urged Rangers chief executive Graham Wallace, who will reveal the findings of his 120 day review tomorrow, to outline where the IPO money went.
The statement continued: "It has now been over four months since Mr Wallace's AGM pledge and we expect, given the length of time it has taken, that this business review will give a full and comprehensive picture of the way forward for the club.
"We expect to see a full breakdown of the how the club arrived at the point where it required to borrow funds simply to complete the current season.
"This should include a full breakdown of where the IPO money went. In particular, detail of the sky high placement costs, related fees and who those fees were paid to and why.
"We expect to see full detail of who will be providing the £30-£50m required to take Rangers back to the level we should be operating at, in the absence of this board accepting the offer of investment from Dave King.
"We also expect to be told exactly when this will be provided, on what terms and a clear plan of how it will be used to rebuild the club both on and off the park.
"We hope that this review will not simply be more, vague, corporate speak. We want to see tangible, measurable progress and firm commitments on the huge investment required."
Meanwhile, Rangers have been linked with former Everton and Liverpool director of communications Paul Tyrrell.