The largest U.S. accounting firms have perfected a remarkably effective behind-the-scenes system to promote their interests in Washington. Their tax lawyers take senior jobs at the Treasury Department, where they write policies that are frequently favorable to their former corporate clients, often with the expectation that they will soon return to their old employers. The firms welcome them back with loftier titles and higher pay, according to public records reviewed by The New York Times and interviews with current and former government and industry officials.
