The letter requests any waivers granted by the White House to appointees be provided to the government ethics office, an independent government agency, by June 1.
The administration has the authority to grant ethics waivers to appointees.
The Office of Government Ethics director, Walter Shaub, said in an interview that the Obama administration similarly granted waivers. But he said the prior administration's waivers were given "under a narrow set of circumstances" and were posted publicly on the Office of Government Ethics' website.
Since then, the OGE has been tasked with assisting the Trump Administration's officials address any potential conflicts of interest so they're able to serve in positions without creating the appearance of using public office for private gain.
But the New York Times reported in mid-April that in at least two instances, the Trump administration "secretly issued" waivers exempting officials from ethics rules. One case, as the New York Times reported, involved Trump's top energy adviser Michael Catanzaro, who worked as a lobbyist on behalf of oil and gas companies until late last year before taking his current post where he advises on issues that would have a direct implication on his former clients.
The White House did not immediately respond to ABC News' request for comment.