BDO USA, LLP is the United States Member Firm of BDO International, a global accounting network. The company is headquartered in Chicago. BDO USA, LLP was founded as Seidman and Seidman in New York City in 1910 by three immigrant brothers: Maximillian L. Seidman, Francis E. Seidman, and Jacob S. Seidman. At that time the accounting profession was in its infancy, with fewer than 2,200 practicing CPAs in the United States. Shortly thereafter in 1913, the 16th Amendment to the United States Constitution was ratified, followed by the Revenue Act of 1913 with new impositions of U.S. Federal income tax enacted by Congress in that year. M. L. Seidman saw the potential of the accountants role to provide tax services to individuals. By 1917, Congress enacted the first revenue bills and the U.S. entry into World War I created the need for corporate income and excess profit taxes. At the same time, federal spending rose to $18.9 billion with 58 percent of the federal revenues provided from income taxes. M.L. Seidman and his siblings, who joined him in his new accounting firm, seized the opportunity to provide tax services to businesses in addition to individuals. An era of expansion began. Fostered by the federal governments conversion of furniture and woodworking companies to aircraft production for the war effort, the firm opened an office in Grand Rapids, Michigan in 1917. Seidman and Seidman quickly established itself as a leader in serving the furniture industry by developing the first effective furniture plant costing system. Today, BDO Seidmans Furniture Industry practice remains in the industry.