•Hunter Biden was indicted in September on federal firearm charges in Delaware.
•Department of Justice Special Counsel David Weiss has been investigating Hunter Biden's alleged criminal conduct since 2019.
Federal prosecutors have filed tax charges against Hunter Biden, in a new criminal case against the US president's son.
The indictment alleges he "engaged in a four-year scheme to not pay at least $1.4m in self-assessed federal taxes he owed for tax years 2016 through 2019".
The nine charges include failure to file and pay taxes, false tax return and evasion of assessment.
Hunter Biden was indicted in September on federal firearm charges in Delaware.
President Joe Biden's 53-year-old son has already pleaded not guilty in the gun case.
The White House is not commenting on the new charges.
Department of Justice Special Counsel David Weiss has been investigating Hunter Biden's alleged criminal conduct since 2019.
Federal prosecutors allege Hunter Biden "spent millions of dollars on an extravagant lifestyle rather than paying his tax bills".
Instead of paying taxes, prosecutors found that Hunter Biden spent his money on "drugs, escorts and girlfriends, luxury hotels and rental properties, exotic cars, clothing, and other items of a personal nature".
The indictment says that the president's son "individually received more than $7 million in total gross income" between 2016 and mid-October 2020, but "willfully failed to pay his 2016, 2017, 2018, and 2019 taxes on time, despite having access to funds to pay some or all of these taxes".
The charge sheet also notes that Hunter Biden had joined the board of directors of Burisma Holdings Limited, a Ukrainian industrial conglomerate, which agreed to pay him an annual salary of about $1m (£795,000).