Here is the short version in approx numbers
Rangers cost approx £45m a year to run. Income with no European champions league football is £35m. With the champions league Rangers make a £10m profit. So huge gamble on making the champions league ever year. Miss it to many times and the debt builds up and that has happened.
Also in the background HMRC have gone after Rangers for using EBT's mainly 10 years ago. They are not saying they are illegal they are not they are saying the way Rangers implemented them was illegal. Potential tax liability is somewhere between £34-£79m depending on penalties applied and who;s numbers you believe. Bottom line is , if Rangers lose the case that cannot pay.
Current chairman purchased the club for £1 and £18m of payment direct to Lloyds to clear the bank debt. This made him the secured creditor.
Now for my opinion bit. He purchased knowing from day one he would take the club into administration at some point. He has run up more debt before doing so. Currently HMRC have not got more than 25% of the debt so cannot stop a CVA happening.
So 2 options
1. club comes out of administration with all those owed getting pennies in the pound
2. he liquidates the club and still owns all the assets as the secured creditor and starts again under a new name
Current Chairman has a history of doing this and although morally wrong I suspect strongly he has all the detail in place and it has been handled by professionals for the last year knowing it was going to happen. He did not cause the debt at Rangers but it certainly looks like he is personally going to make a financially killing out of others misery.
Of course I could be totally wrong and he does a pre-pack and gives all the assets back to the new Rangers

but I suspect the best Rangers can hope for is he rents them back or he sells to a new owner and walks away.
It is looking like a very public example of what is bad and the same time legal in business. The current chairman could make millions on this and have only spent £1 of his own cash!