The Trump Organization was found guilty of all charges in the trial held in New York.
This was established by a jury after two days of deliberation.
The tycoon's holding company is accused of tax fraud for having paid some of its managers without declaring it to the tax authorities.
Donald Trump and his children were not in the dock but it is a verdict with serious effects on the image of the tycoon, candidate for the White House, and on the company's relations with banks and lending institutions.