The IRS, in its official response to the report, said the delinquency rates are lower for federal employees than for the public at large, and said its own employees do the best of any agency.
The Postal Service had the most offenders, with more than 9,000 employees who missed at least two years. The Veterans Affairs Department was runner-up with nearly 6,600 employees.
The Defense Department and the service branches combined for roughly 13,000 cases.
Most of the nonfilers were at the low end of the income scale, with earnings under $100,000. Some 738 of them had incomes of $200,000 or more.