A copy of the complaint was not immediately available. The lawsuit was filed in a New York state court in Manhattan.
The investigation by Attorney General Letitia James has focused on whether the Trump Organization misstated the values of its real estate properties to obtain favorable loans and tax benefits.
James was expected to make an announcement at 11:30 AM EDT (1530 GMT). She has said that the investigation uncovered “significant evidence” that Trump and the company fraudulently valued many of its assets.
The Republican former president has denied any wrongdoing and described James’ probe as a politically motivated witch hunt. James is a Democrat. The Trump Organization has called James’ allegations “baseless.”