WASHINGTON — The number of federal workers and retirees who owe delinquent income taxes jumped nearly 12 percent in 2011, the Internal Revenue Service said Friday.

Nearly 312,000 federal workers and retirees owed more than $3.5 billion in back taxes as of Sept. 30, 2011, the agency said. The year before, about 279,000 workers and retirees owed $3.4 billion.

Overall, the 9.8 million workers included in the data had a delinquency rate of 3.2 percent. That’s better than the general public. The IRS says the delinquency rate for the general public was 8.2 percent.