In news about the Trump administration’s job-slashing effort, one class of federal workers comes up repeatedly: “probationary” employees.

At the Internal Revenue Service, 6,700 people with that status are being let go. At the Department of Health and Human Services, reports indicated the total could be 5,200. The Pentagon announced last week that it would terminate 5,400. At the Forest Service, 3,400 may be cut.

These workers, who generally have less than one or two years of service in their current positions, are particular targets among civil servants because they have the weakest protections. Here’s what else we know about the people being shown the door.

What does being on ‘probation’ mean?

Under the federal code, civil servants remain on probation for one year after they are hired, promoted, demoted or otherwise reassigned. Those in the “excepted” service, meaning they don’t go through normal competitive selection processes, can be on probation for two years.

While on probation, a federal employee can essentially be fired at will, although the person’s superiors need to show that the employee’s “work performance or conduct fails during this period to demonstrate his fitness or his qualifications for continued employment.” (Many termination notices included language about the employee’s supposedly inadequate performance, typically without evidence.) Probationary employees may also appeal if they believe they were fired for partisan political reasons or on the basis of unlawful discrimination.

After employees have completed their probation period, they gain more rights to appeal a termination to the Merit Systems Protection Board. Under those rules for due process, the agency must show that an employee wasn’t doing the job, or that the job was no longer necessary.

Nonprobationary employees are being ousted using a process called “reductions in force,” meant for situations where the agency loses funding or has to suspend a given function for other reasons. That process is also subject to complex rules.

How many probationary workers are there?

Federal records do not officially tag employees who are on probation. The Partnership for Public Service, a nonprofit group focused on improving government personnel practices, has estimated, based on hiring dates and extrapolating from the most recent data release in March 2024, that there are 250,000 of these types of workers across the government; it believes this is an undercount. That’s about 11 percent of the federal civilian work force, not including employees at the Postal Service.

So far, the purge of probationary employees hasn’t gotten close to those numbers, but the cuts do not appear to be over.

Who are they?

According to the Partnership for Public Service’s analysis, about 27 percent of probationary workers are under 30, making them disproportionately young compared with other federal employees.

In the final year of the Biden administration, the government hired a lot of medical professionals, partly to serve veterans’ needs, and cybersecurity experts. Many of these employees have abundant options in the private sector and will be difficult to woo back.

“These are exactly the skills we need,” said Jenny Mattingley, the partnership’s vice president for federal affairs. “That’s why they were just hired, and then we sent them out the door.”

Not all probationary employees are early in their careers, however, and many have had years of experience and specialized training in their roles.

One of them, who requested anonymity out of concern for family safety, maintained charts of the nation’s airspace for the Federal Aviation Administration. The employee, who received a termination letter three weeks before probation would have ended, said she held a master’s degree in geospatial intelligence and had worked in the same role as a contractor for three years before being hired. The worker was one of three members cut from a team of 12.

“I’m worried for air travel and public safety,” said the worker, whose union is helping to appeal the termination, citing consistently positive evaluations and a recent promotion.

How are probationary employees fighting back?

Multiple lawsuits are in the works.

Legal groups swiftly filed a class action complaint on behalf of fired probationary workers with the Office of Special Counsel, the White House office that protects whistle-blowers. On Monday, citing a lack of proper procedure, the head of that office recommended that terminations be paused while they were investigated. Those requests are now before the Merit Systems Protection Board, a panel of three judges that adjudicates federal personnel disputes.

Separately, federal employee unions sued the government over the White House’s many types of mass firings. A judge denied a temporary injunction in that case, saying it must be brought before the Federal Labor Relations Authority.

In another legal action, a group of unions sued the Office of Personnel Management, which manages the civil service, saying the agency didn’t have the authority to order the firings. That case remains active.

Niraj Chokshi contributed reporting.