Allen H. Weisselberg, an accountant and one of Donald J. Trump’s most trusted lieutenants, admitted before Judge Juan Merchan in a Lower Manhattan courtroom on August 18 that he had conspired with the former president’s company to commit numerous crimes related to tax fraud.

Mr. Weisselberg’s guilty plea painted a damning picture of the company, which now faces significant financial penalties if it loses its own trial on similar charges.

Under the plea deal, Mr. Weisselberg must pay nearly $2 million in taxes, penalties and interest after accepting lavish off-the-books perks from Mr. Trump and his company, including leased Mercedes-Benz automobiles, an apartment on Manhattan’s Upper West Side, and private tuition for his grandchildren. In exchange for testifying at a trial scheduled in October that names the Trump Organization as complicit in various tax schemes, Mr. Weisselberg is likely to receive a five-month jail sentence and, with time credited for good behavior, might serve as few as 100 days.