filed a lawsuit Monday accusing IRS agents of "repeatedly and intentionally" publicly sharing his private tax return information while they investigate him.
Those agents "have targeted and sought to embarrass Mr. Biden" by disclosing confidential information about his private tax matters to the media, the president's son alleged in the in federal court in Washington, D.C.
Biden wants a court to declare that the IRS unlawfully revealed his tax information and award him $1,000 in damages for each unauthorized disclosure.
The lawsuit comes days after Biden, 53, was indicted on three criminal counts related to his possession of a handgun.
Less than two months earlier, Biden had neared a plea deal with prosecutors on misdemeanor charges that he failed to pay federal taxes on more than $1.5 million annually in 2017 and 2018. He was also prepared to enter into a separate pretrial diversion agreement related to the gun matter.
But the whole arrangement during a dramatic court hearing in July. Instead of locking in the deal, Biden pleaded not guilty to the tax charges, while his attorneys have insisted that the deal for the gun charge was agreed and is valid.
On Monday afternoon, a judge noted that Biden wants his initial court appearance in the gun-possession case to be held via video conference, while the Department of Justice opposes that request. The judge ordered Biden's attorneys to file a short court brief in support of his request by Tuesday at the latest.
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Biden's attorney insisted in Monday's court filing that the new lawsuit against the IRS "is not about the legitimacy of the IRS investigation of Mr. Biden over the past five years or any decision to penalize Mr. Biden for any failure to comply with his obligations under the tax laws."
The 27-page complaint singles out two IRS agents, Gary Shapley and Joseph Ziegler, and their lawyers for allegedly "engaging in a campaign to publicly smear Mr. Biden" by disclosing his tax information in more than 20 nationally televised interviews and multiple public statements.
Shapley and Ziegler had stepped forward as whistleblowers to accuse the Department of Justice of misconduct related to the yearslong tax probe of President 's son. But their conduct extended beyond the bounds of their whistleblower status, Hunter Biden's attorney alleged.
Shapley's legal team in a statement Monday morning called the lawsuit "another frivolous smear by Biden family attorneys trying to turn people's attention away from Hunter Biden's own legal problems and intimidate any current and future whistleblowers."
Neither Shapley nor his attorneys "ever released any confidential taxpayer information except through whistleblower disclosures authorized by statute," they said in the statement to NBC News.
Hunter Biden's attorney, Abbe Lowell, also sent a letter Monday morning to House Ways and Means Committee Chairman Jason Smith, R-Mo., challenging claims that Biden owed large tax amounts during certain years, including 2018.
"I am writing to let you know that your agents and you are wrong," Lowell wrote. "Pending final development of facts impacting Mr. Biden's 2018 tax year, it appears Mr. Biden will be due a refund for that tax year."
The IRS declined to respond to CNBC's request for comment on the lawsuit.
