a. revenue agencies.FEEDBACK: One of the first actions Congress took under President George Washington was to create the Department of the Treasury, and probably its oldest function is the collection of taxes on imports, called tariffs. Now part of the Department of Homeland Security, federal customs agents are located at every U.S. seaport and international airport to oversee the collection of tariffs. But far and away the most important of the revenue agencies is the IRS, a bureau within the Treasury Department.