Updated

Hunter Biden did not report “approximately $400,000” in income he collected from his position on the board of Ukrainian natural gas firm Burisma Holdings when he joined in 2014, according to an attorney for his firm who noted that his tax returns needed to be amended, a new email obtained by Fox News shows.

The memo dated Jan. 16, 2017, one of multiple new emails obtained by Fox News, detailed President-elect Joe Biden’s son's income for the years 2013 through 2015 for tax purposes.

Biden, last week, confirmed that he was under federal investigation for his "tax affairs."

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The email, which was first reported by NBC News, was sent to Hunter Biden from Eric Scherwin, who at the time served as president of Rosemont Seneca. Fox News could not verify its authenticity; neither Scherwin nor Hunter Biden attorney George Mesires immediately responded to Fox News' requests for comment. 

"In 2014, you joined the Burisma board and we still need to amend your 2014 returns to reflect the unreported Burisma income," Scherwin wrote to Hunter Biden. "That is approximately $400,000 extra so your income in 2014 was closer to $1,247,328."

The email stated that in 2013 Hunter Biden’s taxes reported “$833,614 in income,” in 2014 “your taxes reported $847,328 in income. (To be amended at $1,247,328),” and in 2015 reported $2,478,208 in income.”

Scherwin described Hunter Biden’s income in 2013 and 2014 as “normal years” when his income “was based pretty much solely on income from Rosemont Seneca and Boies.”

Scherwin went on to explain Hunter Biden’s “increased income in 2015,” noting that he collected “$166,666 from Burnham (for RSA), $216,000 from Boies, $365,403 from Owasco (for RSA), $300,000 one time payment from Eudora (for the 1/3 of CitizensRx).”

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“The above represents all the cash you received directly,” Scherwin wrote. “In addition, you reported $1,000,000 of income that all went to RSB and you reported $188,616 in income that also went to RSB.” 

He added: “You didn’t receive this in cash and it is in reality 'phantom income.'” 

Scherwin went on to break down Hunter Biden’s income further, adding: “Since you couldn’t have lived on approximately $550,000 a year, you ‘borrowed’; some money from RSB in advance of payments.” 

This email appeared to have come as part of a discussion between Scherwin and Hunter Biden about his divorce — specifically alimony and child support payments. 

In an email sent the following day, Jan. 17, 2017, also obtained by Fox News, Scherwin broke down an example of child support payments. 

“As an example, if you were to provide $10,000 in alimony and $10,000 in child support, you would need $30,000 a month in pre-tax income or $360,000 a year,” Schwerin wrote, adding another scenario, including where Hunter Biden could pay “tuition for the girls.” 

“Therefore, the above scenario would require you to make $1,080,000 a year,” he wrote. “Anything beyond that would be money for your use.” Scherwin added: “This does NOT include money for back taxes, etc. however.” 

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Joe Biden's transition team declined to comment. Last week, the Biden-Harris transition team stated: “President-elect Biden is deeply proud of his son, who has fought through difficult challenges, including the vicious personal attacks recent months, only to emerge stronger.”

Hunter Biden has been scrutinized for his role on the board of Burisma. 

“I learned yesterday for the first time that the U.S. Attorney’s Office in Delaware advised my legal counsel, also yesterday, that they are investigating my tax affairs,” Hunter Biden said in a statement last week. “I take this matter very seriously but I am confident that a professional and objective review of these matters will demonstrate that I handled my affairs legally and appropriately, including with the benefit of professional tax advisors.”

A well-placed government source told Fox News that Hunter Biden has been a subject/target of the grand jury investigation. According to the source, a "target" means that there is a "high probability that person committed a crime," while a "subject" is someone you "don't know for sure" has committed a crime. 

The source said President-elect Biden was not a subject of any grand jury investigation at this time.

The source also told Fox News that this investigation was predicated, in part, by Suspicious Activity Reports (SARs) regarding suspicious foreign transactions. 

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Another source familiar with the investigation told Fox News that the SARs were regarding funds from "China and other foreign nations.”

A Treasury Department official, who did not comment on the investigation, spoke broadly about SARs, telling Fox News that SARs are filed by financial institutions "if there is something out of the ordinary about a particular transaction." 

The official told Fox News that the mere filing of an SAR does not mean there has been a criminal act or violation of regulations but instead flags that a transaction is "out of the ordinary" for the customer. The official noted, though, that an SAR could be part of a money-laundering or tax investigation.

The investigation, according to a source familiar with the matter, began in 2018.

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Two sources familiar with the investigation told Fox News that the investigation includes looking at a laptop purportedly belonging to Hunter Biden. 

In October, Fox News first reported that the FBI subpoenaed a laptop and hard drive purportedly belonging to Hunter Biden in connection with a money-laundering investigation in late 2019.