Formula 1 tycoon Bernie Ecclestone has gone to court to challenge the basis of assessments that have left him facing a UK tax claim of more than £1bn.
The 84-year-old, at the F1 helm for 40 years, wants the assessments quashed, and HM Revenue and Customs (HMRC) held to an earlier April 2008 agreement.
The new figure is believed to cover the period from the tax year ended 5 April 1996 to tax year ending 5 April 2006.
Mr Ecclestone's lawyers have applied for permission to seek judicial review.
They say that following the April 2008 settlement, HMRC should not have attempted to make the tax assessments.
High Court judge Mr Justice Kenneth Parker ruled that one of the billionaire's grounds for review was "arguable".
But the judge said that Mr Ecclestone's application should be stayed while his legal team pursued alternative proceedings in the Commercial Court.
He also said the tax and interest being demanded from Mr Ecclestone was more than £1bn.
Mr Justice Parker said HMRC had written to Mr Ecclestone in December saying he had withheld information that made the 2008 agreement invalid.
The case revolves around the Ecclestone family's Bambino trust which was set up in Liechtenstein in 1997 for the benefit of Mr Ecclestone's now ex-wife, Slavica, and daughters Tamara and Petra.
The UK tax authorities re-opened their investigation of Bambino after a high-profile bribery case in Germany last year, said the judge.
In that trial it was disclosed that the trust had made a payment to German banker Gerhard Gribkowsky whom Mr Ecclestone claimed had threatened to report him to British tax collectors.
Mr Ecclestone has repeatedly said he has nothing to do with the management of the trust funds and does not benefit from them.
When contacted by BBC Sport about the latest court hearing, Mr Ecclestone said: "The lawyers are dealing with it. That's why it's in court. It's very technical."
Asked if he was worried about the developments, he answered: "No".