WASHINGTON — It has been called President Biden’s “shadow army,” described as a strike force to shake down small businesses with assault rifles and likened to a militia of auditors on search-and-destroy missions.A decades-long Republican antipathy toward the Internal Revenue Service has reached a new level of enmity with the passage of a Democratic-backed bill that gives the agency $80 billion to beef up its ability to go after tax cheats. The legislation, which Mr. Biden signed into law this week, will allow the beleaguered agency to hire more than 80,000 employees, upgrade outdated technology systems and improve its ability to respond to taxpayers.The agency’s staff is the same size today as it was in 1970, when it processed far fewer individual tax returns. Its enforcement staff has fallen more than 30 percent since 2 …
