Rangers have filed court papers signalling their intention to go into administration.
STV can exclusively reveal the Ibrox club lodged the notice at the Court of Session in Edinburgh at lunchtime on Monday.
In a statement released on Monday, the club said the tax bill it faces from HM Revenue and Customs could be "substantially more than the £50m reported" which the club would be "unable to pay". Owner Craig Whyte later revealed in an interview with Sky Sports News that the tax bill could be as much as £75m.
It is understood the papers are the first step in any formal administration process. They now have ten business days in which to declare administrators have taken over the running of the Glasgow-based club.
The papers, signed off by Rangers directors including owner Craig Whyte, were lodged with the court, as well as supporting documentation that showed that the Ibrox club "is or is likely to become unable to pay its debts" and "is not in liquidation" under the terms of the Insolvency Act 1986.
In a statement released on the club website, the club owner said there is no "realistic or practical" alternative to preparing for administration.
As Mr Whyte tried to address fans on the steps of Ibrox on Monday evening, he was heckled by waiting Rangers fans.
Rangers said "further investment in the club from any source would be impossible as the threat of winding up by HMRC cannot be removed" while the club has proposed a creditors voluntary agreement proposal to HMRC in which "creditors would be paid and provision made for the legacy HMRC case, commonly known as the 'big tax' case."
STV understands owner Mr Whyte, director of operations Ali Russell and board member Andrew Ellis, had a meeting with manager Ally McCoist on Monday to inform him of the news.
On Monday the club stated that "should the club proceed into administration, the appointed administrators will in all likelihood implement a cost-cutting programme and staffing levels will be reviewed across all departments of the club's business."
Rangers confirmed "the club has engaged Duff and Phelps, a specialist restructuring practice to assist in finding a solution to the present position."
HM Revenue and Customs guidelines state: "The appointment of the administrator will take effect within ten business days of the date the notice of intention is filed."
This period allows the company to speak to creditors to see if they reach an agreement. If they enter administration the Scottish Premier League champions will automatically be docked ten points.
A statement from the SPL read: "If an SPL club is the subject of an Insolvency Event, which would include the appointment of administrators, a ten point deduction would apply immediately to its total points in the League Championship.
"The club would also be embargoed from registering any new players with the SPL.
"A notice of the intention to appoint administrators alone does not trigger the sporting sanctions - it is the actual appointment of administrators which does.
"If administrators are appointed we will seek an early meeting with them to discuss their plans for Rangers FC".
The club claimed on Monday that should a creditors voluntary agreement be approved "within a month, [it] would minimise any points deduction and enable the club to participate in European football next season."
Rangers FC are currently awaiting the result of the tax case with HM Revenue and Customs in relation to the club's use of an Employee Benefits Trust to pay players and staff. It is thought the decision to lodge court papers means the result of this tax case is likely to be known imminently.
The First Tier Tax Tribunal confirmed the decision in the case against Rangers has not been published, although it could not confirm whether or not the club had learnt of it ahead of it being released publicly.
The Court of Session confirmed to STV that papers signalling the intention to appoint administrators had been received from the club's solicitors acting on behalf of their directors.
In a statement released on the club's website, Mr Whyte said: "It is extremely disappointing the club's finds itself in this position but decisions have to be taken to safeguard the long-term survival and prosperity of the club both on and off the field. The harsh reality is that this moment has been a long time coming for Rangers and its roots lie in decisions taken many years ago. If we do not take action now the consequences and the risks to the club are too great.
"In addition to the HMRC issues, it has been abundantly clear to me the club faces serious structural and financial issues which will continue unless they are addressed.
"There is no realistic or practical alternative to our approach as HMRC has made it plain to the club that should we be successful in the forthcoming tax tribunal decision, they will 'appeal, appeal and appeal again' the decision. This would leave the club facing years of uncertainty and also having to pay immediately a range of liabilities to HMRC. Even if the club were to succeed in the tax tribunal, it would still face substantial liabilities. Zero liability will not happen.
"Whilst it appears that a consensual restructuring looks unlikely outside of a formal insolvency procedure, the above steps, if agreement cannot be reached with HMRC, will bring an end to the legacy threat of closure and will provide stability required to enable the required investment to be made into the future of the Club.
"I can, however, reassure Rangers supporters that the club will continue and can emerge as a stronger and financially fitter organisation that will compete at the levels of competition our fans have come to expect. At this point I would ask all Rangers supporters to continue to show the tremendous support they have shown to the club, Ally McCoist, his management team and the players."
A spokesman for HMRC told STV: "If there are any outstanding bills as part of a tax debt at Rangers then they will be accounted in the calculations made by any administrator that’s appointed.
"The tribunal case is totally separate and we are still awaiting a decision on that, which is believed to be a few weeks away yet."
Rangers are expected to make a statement to London-based Plus Stock Exchange about their intention to go into administration.
The club was suspended from trading shares on the stock exchange after failing to file audited accounts on time earlier this year.
Former chairman Alastair Johnston, who last week called for the Insolvency Service to investigate the financial arrangements at the club following Mr Whyte's takeover, accused Mr Whyte of putting his own interests first.
He said: “Much as though it was anticipated it’s still a shocking experience to know the process has at least been initiated.
“My concern all along is that all the major players in the game whether it’s Ticketus, HMRC or especially Craig Whyte will be looking after their own interests.
“That’s the sadness when I think about the 26,000 minority shareholders, all the small businesses that are creditors of the company that enjoyed doing business with Rangers and of course all the fans that have invested a lifetime of passion.”
Mr Whyte confirmed recently that he had used four years' future season ticket sales to secure a £20m loan from London company Ticketus.
On Monday afternoon, Ticketus' parent company Octopus Investments refused to comment on the news as it was a "confidential client relationship". The company would not confirm whether or not Ticketus was currently pursuing Rangers for repayment.
Sports Minister Shona Robison said on Monday: "I understand that Rangers and HMRC are continuing dialogue and we obviously want to see an agreement which will protect jobs and enable the club to stay in business.
"Rangers is a crucial part of Scotland's national game, and our interest is ensuring that a resolution can be arrived at between HMRC and the club to deliver these vital objectives."
Former owner Sir David Murray did not respond to STV's attempts to contact him regarding the news on Monday.