The White House says the president paid "no more tax than legally required"
The controversy over Donald Trump's tax affairs has been thrust back into the US political spotlight, after details from his 2005 return were leaked to an investigative journalist.
The White House responded angrily to the leak of the president's 12-year-old federal tax return but also confirmed the details contained in its two pages.
Mr Trump has consistently refused to release his tax returns, a break with presidential tradition.
It has led to accusations that the billionaire tycoon has something to hide in his finances.
The 2005 return revealed that Mr Trump paid federal taxes of US$38m (€35.7m) on his income of $150m (€141m).
He also wrote off $100m (€94m) in business losses.
Additional pages containing more detailed information on bank accounts, loans and investments were not included in the leak.
Journalist David Cay Johnston told MSNBC he had received the tax return anonymously through the post.
It was revealed on the primetime Rachel Maddow Show.
Shortly before the broadcast, a White House official said: "You know you are desperate for ratings when you are willing to violate the law to push a story about two pages of tax returns from over a decade ago."
It added that Mr Trump had paid "no more tax than legally required".
Mr Trump has always said he cannot release his tax returns because of an on-going audit, something tax experts have questioned.
His advisers have consistently said that only the media, and not the American people, care about the issue.
But this leak has led to speculation over who may have been responsible and whether further tax returns might be forthcoming.
Johnston, who has written a book on Mr Trump, hinted that he would not be surprised if the president himself was behind the leak.
Trump's administration continues to face questions over alleged collusion with Russia during last year's election.
The president is also fighting high-profile battles over immigration and healthcare. The White House remains locked in combat with the media.
"It is totally illegal to steal and publish tax returns. The dishonest media can continue to make this part of their agenda, while the president will focus on his, which includes tax reform that will benefit all Americans," said the White House official.
MSNBC said it believed it had acted in accordance with the law in reporting the leaked tax return.
Just before November's election, the New York Times revealed a partial tax return for Trump from 1995 which showed a $916m (€862m) tax deduction.
It would have allowed Mr Trump to avoid federal income tax for up to 18 years.