Donald Trump overstated his net worth by as much as $3.6bn between 2011 and 2021, the attorney general of New York state said in a court filing first reported by CNBC on Friday – a $1.4bn increase on a previous filing that put the top amount at $2.2bn. In the new filing, CNBC said, the attorney general, Letitia James, said she was “still [making] a conservative estimate” about by how much Trump’s net worth was overstated in annual financial statements. Trump’s net worth was exaggerated by between $1.9bn and $3.6bn, the filing said. In the civil fraud suit, James is suing Trump, his adult sons, Donald Trump Jr and Eric Trump, and the Trump Organization for $250m. The state is also seeking stringent professional penalties. Trump’s oldest daughter, Ivanka Trump, was dropped from the suit this year. In the new filing on Friday, prosecutors said valuations experts arrived at the new figure for Trump’s overestimations of his worth by applying financial methods “market participants would consider when determining estimated current value”, ABC News reported. Prosecutors added: “After factoring in these and other fundamental considerations that any informed buyer and seller in the marketplace would take into account, Mr Trump’s net worth would be further substantially reduced by between $1.9bn to $3.6bn per year, which is still a conservative estimate.” Trump is the clear frontrunner for the Republican presidential nomination. Denying wrongdoing, he claims political persecution by James, a Democrat. Trial is set to begin on 2 October. Earlier this week, the judge in the case denied a Trump attempt to delay the trial which he said was “completely without merit”. Both sides have sought summary judgment. The new filing from James came in opposition to such a move by Trump. As previously, James cited a “mountain of evidence” that defendants “engaged in fraudulent business transactions with the capacity or tendency to deceive”. He faces another civil trail, for defamation arising from an allegation of rape by the writer E Jean Carroll, having already been found liable for defamation and sexual abuse and ordered to pay $5m. The judge in the case has said Trump has been adjudicated a rapist. He also faces 91 criminal charges under four separate indictments, for state (13 charges) and federal (four) election subversion, retention of classified documents (40) and hush-money payments during the 2016 election (34). Trump’s finances have been a matter of public fascination since he entered presidential politics in 2015. Refusing to follow convention, he did not release his tax returns, claiming to be prevented from doing so because he was under audit. Audits do not preclude release of tax returns. The New York Times reporter Maggie Haberman has revealed how Trump came up with that excuse literally on the fly, on a campaign plane. Award-winning reporters and Democrats in Congress, meanwhile, have revealed Trump’s tax affairs to the world, showing how he inflated or deflated his worth and that of his assets.