In 1996, Ms Trump—then Knauss—was paid for modelling work undertaken in the United States while travelling on a visitor—or tourist—visa, violating the terms of entry, according to documents obtained by the Associated Press.
The first lady allegedly earned more than $20,000 (£16,000) in the seven weeks before she acquired legal permission to work in the country.
She went on to apply for a green card in 2001 and became a naturalised US citizen in 2006 without disclosing any past indiscretions.
Under new rules brought in by Mr Trump last month, immigration officials are now required to prioritise the removal of any foreign national who has “engaged in fraud or willful misrepresentation in connection with any official matter or application before a government agency”.
Ms Trump put herself into this category when she violated her visa and did not disclose the indiscretion when applying for future travel and residency permits, a pair of immigration lawyers told the Slate website.
She would likely have faced deportation under Mr Trump's 25 January executive order if it had been in effect and she had been caught in the 1990s, or in fact at any point before becoming a naturalised US citizen in 2005.
Hasan Shafiqullah, deputy attorney in charge of the immigration law unit at the Legal Aid Society, said Ms Trump would have been at serious risk of deportation if caught in the 90s by a time-travelling Trump administration.
“If the current executive order on interior enforcement and the related Homeland Security memoranda on interior enforcement had been in effect at that time , then she would have certainly been an enforcement priority,” he added.
New York City immigration specialist Cheryl David agreed.
She said that if Ms Trump did in fact undertake paid work while in the United States a tourist visa, she “definitely violated her status, and if it came to immigration’s attention, yeah, they certainly could put her into removal proceedings”.
The controversial orders Donald Trump has already issued
The controversial orders Donald Trump has already issued
1/9 Trump and the media
White House Press Secretary Sean Spicer takes questions during the daily press briefing
2/9 Trump and the Trans-Pacific Partnership
Union leaders applaud US President Donald Trump for signing an executive order withdrawing the US from the Trans-Pacific Partnership negotiations during a meeting in the Roosevelt Room of the White House in Washington DC. Mr Trump issued a presidential memorandum in January announcing that the US would withdraw from the trade deal
3/9 Trump and the Mexico wall
A US Border Patrol vehicle sits waiting for illegal immigrants at a fence opening near the US-Mexico border near McAllen, Texas. The number of incoming immigrants has surged ahead of the upcoming Presidential inauguration of Donald Trump, who has pledged to build a wall along the US-Mexico border. A signature campaign promise, Mr Trump outlined his intention to build a border wall on the US-Mexico border days after taking office
4/9 Trump and abortion
US President Donald Trump signs an executive order as Chief of Staff Reince Priebus looks on in the Oval Office of the White House. Mr Trump reinstated a ban on American financial aide being granted to non-governmental organizations that provide abortion counseling, provide abortion referrals, or advocate for abortion access outside of the United States
5/9 Trump and the Dakota Access pipeline
Opponents of the Keystone XL and Dakota Access pipelines hold a rally as they protest US President Donald Trump's executive orders advancing their construction, at Columbus Circle in New York. US President Donald Trump signed executive orders reviving the construction of two controversial oil pipelines, but said the projects would be subject to renegotiation
6/9 Trump and 'Obamacare'
Nancy Pelosi who is the minority leader of the House of Representatives speaks beside House Democrats at an event to protect the Affordable Care Act in Los Angeles, California. US President Donald Trump's effort to make good on his campaign promise to repeal and replace the healthcare law failed when Republicans failed to get enough votes. Mr Trump has promised to revisit the matter
7/9 Donald Trump and 'sanctuary cities'
US President Donald Trump signed an executive order in January threatening to pull funding for so-called "sanctuary cities" if they do not comply with federal immigration law
8/9 Trump and the travel ban
US President Donald Trump has attempted twice to restrict travel into the United States from several predominantly Muslim countries. The first attempt, in February, was met with swift opposition from protesters who flocked to airports around the country. That travel ban was later blocked by the Ninth Circuit Court of Appeals. The second ban was blocked by a federal judge a day before it was scheduled to be implemented in mid-March
SANDY HUFFAKER/AFP/Getty Images
9/9 Trump and climate change
US President Donald Trump sought to dismantle several of his predecessor's actions on climate change in March. His order instructed the Environmental Protection Agency to reevaluate the Clean Power Plan, which would cap power plant emissions
In theory, Ms Trump's citizenship could still be revoked on the grounds that she willfully misrepresented or concealed facts relevant to her naturalisation.
Historically, this has only been done in extreme cases, with terrorists and war criminals among those targeted.
But Mr Trump has ordered the Department of Homeland Security (DHS) to actively target and deport people who were technically violating the rules, insisting that if immigrants violate US law in any way, “they have to go".
These include those whose indiscretions were considered too minor to act on by Barack Obama and other presidents before him.
Documents released by the DHS this week revealed that immigration officials intend to put his instructions into practice.
A lawyer representing Ms Trump said the documents obtained by the AP were not familiar to him but did not otherwise challenge their veracity or deny that she had done the work which would have violated the terms of the B1/B2 visitor visa she initially travelled on.