The U.S. Internal Revenue Service will lay off about 6,700 employees on Thursday, in a restructuring that could strain the tax-collecting agency’s resources during the critical tax-filing season, a person familiar with the matter said. The workers being cut are probationary employees who have typically been at the agency for less than one to two years, and enjoy fewer protections than longer-term workers. The IRS has a total of roughly 17,000 probationary employees. The reductions at the IRS come amid a broader slashing of personnel across the federal government at the directive of President Donald Trump and Elon Musk, who...