EXCLUSIVE

Lisa Marie Presley is about to file a lawsuit against her former financial managers, claiming they squandered more than $100 million over 10 years, but the company says Lisa Marie is broke because she's a spendthrift.

TMZ has obtained a copy of the lawsuit which could be filed as early as today. She claims financial guru Barry Siegel sold 85% of her interest in Elvis Presley Enterprises (EPE) and then gave the money to Robert F.X. Sillerman as a way of ingratiating himself with the famous investor. She says the investments tanked and left her broke.

Among the alleged misdeeds -- Presley says unbeknownst to her Siegel spent $9 million of her money to buy an English estate and couldn't make the balloon payment on the property.

She also says Siegel stopped paying her taxes in 2012 which left her with a tax bill of $7 million.

She says as of May 30, 2016, the trust was depleted and only had $14,000 in cash and she had $500,000 in credit card debt.

We're told Siegel's position is that Lisa Marie overspent herself into destitution. In fact, he says she went broke twice because of her spending habits. He says as early as 2003 Lisa Marie was $20 million in debt and he was the one who righted the ship. Siegel says he tried hard to get her to stop her excessive spending over the next 10 years but it fell on deaf ears.

We're told Siegel plans to countersue Presley for $800,000 in unpaid management fees.

Lisa Marie's lawyer, Amjad Khan, tells TMZ, "Lisa Marie Presley has been betrayed by her former Trustee, Barry Siegel and Provident Financial Management -- Hollywood money managers to stars like Al Pacino and Rob Thomas."