US government workers who have been buffeted by President Donald Trump’s chaotic return to power face more uncertainty on Monday, when many of them will be required to justify their jobs to Elon Musk, the chainsaw-wielding billionaire tasked with slashing the federal budget.

Musk’s demand for the nation’s civil-service workers to submit a summary of their work by 11:59pm Eastern time (9:59am PKT) has opened up fissures in Trump’s administration.

Agencies like the Drug Enforcement Administration and the Federal Communications Commission have told employees to comply.

But many others, including the Departments of Defence, Homeland Security, Education and Commerce, have ordered workers not to respond.

The Department of Health and Human Services told its workers to cooperate, then later told them to hold off while it figured out how to “best meet the intent” of Musk’s unusual directive.

Workers at the Consumer Financial Protection Bureau also received Musk’s email, even though they have been already ordered to cease working.

Musk, the world’s richest person, has led a downsizing effort that has laid off more than 20,000 workers and offered buyouts to another 75,000 across wide swaths of the 2.3-million strong civil service, from bank regulators to park rangers.

In some cases, the government has scrambled to re-hire workers who perform critical functions like nuclear weapons oversight and bird flu response.

Trump’s administration said late on Sunday it would fire 1,600 workers at the US Agency for International Development and put nearly all remaining personnel on leave. Trump has already halted almost all of the agency’s funding and operations, throwing global humanitarian relief efforts into chaos.

The mass firings have suddenly thrust financial insecurity on workers who had counted on their jobs to provide a secure income.

Charles Farinella, a fired IRS agent in New York, said he was trying to figure out whether he should cancel an upcoming dentist appointment because he has not been told whether he still has coverage through his job.

“I don’t know what I’m going to do at this point in time. I might have to look to sell my house, because I don’t have a severance or anything,” he said. “I feel pretty much devastated.”

Musk’s job-slashing effort has rippled into the wider US economy as well, forcing companies that do business with the government to lay off their own workers and defer payments to vendors.

One company that works with USAID, Chemonics, said in a court filing last week that it had furloughed 750 employees, 63 per cent of its workforce.

Musk has revelled in the chaos, even wielding a chainsaw at a conservative political conference last week. The chief of Tesla and social media platform X has said he aims to cut $1 trillion from the government’s $6.7tr budget.

Trump has promised to exempt popular health and retirement benefits, which puts nearly half of the budget effectively off limits, but Musk said he would examine those programs for fraudulent payments.

“We are increasingly optimistic that, as the immense waste & fraud are eliminated from Social Security & Medical that there is potential to increase actual dollars received by citizens & better healthcare!” he wrote on X on Sunday.

The Government Accountability Office, a watchdog agency, estimates the total of fraud and improper payments could be as high as $521 billion annually, equal to 8pc of spending last year.

Opposition Democrats say the budget-cutting effort violates Congress’s authority to control government spending, but they have been largely powerless to stop it.

Republicans in Congress have cheered the effort as they prepare sweeping legislation of their own to enact trillions of dollars in tax cuts.

But some Republicans have faced boos from voters back home who have said Musk is overstepping his authority.