A day without pay, the first of 11 through September, comes this week for more than 650,000 people who hold civilian jobs with the Defense Department.
Officials worry that the Pentagon will be hit even harder by layoffs in 2014 if automatic budget cuts continue.
The Pentagon says roughly 85 percent of the department's nearly 900,000 civilians around the world will be furloughed one day each week over the next three months. But while defense officials have been able to shift money around to limit the furloughs this year, thousands of civilian, military and contract jobs could be on the chopping block next year.
Defense Secretary Chuck Hagel is expected to provide more details early next week on how the next wave of across-the-board budget cuts will affect the department.