Watkins Meegan, the regional Bethesda-based accounting and tax firm, will combine with the larger national accounting firm CohnReznick in November, the companies announced Wednesday.

The firms have signed a letter of intent to combine practices effective Nov. 1. The newly combined firm will be called Cohn­Reznick, and the firm’s current co-chief executives will keep their roles.

The union will create a $600 million firm with about 2,750 employees across the United States, including 800 in the Washington area.

Watkins Meegan has about 200 employees in Bethesda, Tysons Corner, Herndon and Annapolis and annual revenue of $40 million. The niche firm specializes in government contractors, the real estate and construction industries, and the not-for-profit and hospitality industries.

New York-based CohnReznick has annual revenue of more than $500 million and has 2,500 employees in 26 U.S. offices in Georgia, Texas, Maryland, Massachusetts, North Carolina, Illinois, New Jersey, Connecticut, New York, California, Pennsylvania, Virginia and the Cayman Islands. About 600 of those employees are in the Washington area.

The move will bolster Cohn­Reznick’s presence in the Washington region, according to a joint statement from both firms. Watkins Meegan managing partner Mike Micholas will continue to serve as part of the senior management team in Washington.

“We are continually looking at quality firms whose specialties complement our own,” said Ken Baggett, co-chief executive of CohnReznick. “We are very pleased about the synergies created by this combination.”

Capital Business is The Post’s weekly publication focusing on the region’s business community. For more Washington business news, go to www.capbiz.biz.