The emails came shortly after Elon Musk, the billionaire head of the Trump administration's Department of Government Efficiency, posted on the social media site X that not responding to the email request would be viewed as a resignation.
"All federal employees will shortly receive an email requesting to understand what they got done last week," Musk posted on X.
"Failure to respond will be taken as a resignation."
Musk issued his post just hours after President Donald Trump posted on his own social media network, Truth Social, that DOGE should get more aggressive in its attempts to downsize and reshape the 2.3 million-strong federal workforce.
As of Saturday evening, emails were sent to employees across federal agencies, including the Securities and Exchange Commission, National Oceanic and Atmospheric Administration, the Centers for Disease Control and Prevention and others with the subject line, "What did you do last week?"
The email, seen by Reuters, asks employees to reply with five bullet points summarising "what you accomplished at work last week," and to copy their managers.
It was sent from a human resources address from the Office of Personnel Management, and gives employees until midnight on Monday to respond.
It is unclear what legal basis Musk has to terminate federal workers if they fail to respond to his request and what would happen to employees that cannot detail confidential work.
Some federal judiciary employees received the email on Saturday from OPM, even though the court system is not part of the executive branch, people familiar with the matter said.
The Administrative Office of the US Courts, the judiciary's administrative arm, did not immediately respond to requests for comment.
Workers at the Consumer Financial Protection Bureau also received the email, according to people with knowledge of the matter.
However, most agency staff had been ordered not to perform any tasks since early this month, creating a conundrum. The agency is also under temporary court order not to resume mass firings pending the outcome of legal proceedings.
A spokesperson for DOGE did not immediately respond to a request for comment.
The AFGE, the union representing federal employees, said in a statement it will challenge any "unlawful terminations".
"Once again, Elon Musk and the Trump administration have shown their utter disdain for federal employees and the critical services they provide to the American people," said Everett Kelley, the AFGE's president.
The Trump administration's fast-paced and controversial process to reduce government spending by shrinking the federal workforce spearheaded by Musk and his young aides at the cost-cutting DOGE has led to haphazard firings that resulted in numerous mistakes and forced several agencies to quickly rehire vital employees, such as those working on nuclear safety, defence and power generation.
