WASHINGTON — The Trump administration pushed out a top Treasury Department official this week after he refused to give Elon Musk’s cost-cutting team access to the government’s vast payment system, part of a bid by the so-called Department of Government Efficiency to choke off federal funding.

David Lebryk, a career civil servant who oversaw the more than 1 billion payments that the federal government makes every year, was placed on administrative leave this week after resisting requests from Musk’s lieutenants, according to people familiar with the circumstances, who spoke on the condition of anonymity to describe sensitive internal dynamics.

On Friday, Lebryk — who had briefly served as acting Treasury secretary until the confirmation of Scott Bessent this week — told colleagues that he would retire after more than 35 years of working for the government.

Lebryk’s abrupt departure raises questions about whether Musk will now gain control of the payment system — and, if so, how he could use it. His exit also underscores the extraordinary amount of power that Musk, whose current employment status inside the federal government remains unclear, is accumulating at the opening of the second Trump administration.

Musk, a billionaire, has dispatched aides across the bureaucracy to try to radically reduce spending. He has told Trump administration officials that he aims to take control of the Treasury computers used to complete payments in order to identify fraud and abuse, according to three people familiar with his remarks.

The Treasury Department executes payments on behalf of agencies across the government, disbursing $5.4 trillion, or 88% of all federal payments, in the last fiscal year. The system is run out of the Bureau of the Fiscal Service, a little-known but critical office that is responsible for getting money to Social Security recipients, government employees, contractors and others.

Former Treasury officials said they were not aware of a political appointee ever seeking access to details of the payment system, which includes reams of sensitive personal information about American citizens. Control of the system could give Musk’s allies the ability to unilaterally cut off money intended for federal workers, bondholders and companies, and open a new front in the Trump administration’s efforts to halt federal payments.

“The fiscal service performs some of the most vital functions in government,” Lebryk wrote to his colleagues in an email announcing his retirement Friday, according to a copy of the email viewed by The New York Times. “Our work may be unknown to most of the public, but that doesn’t mean it isn’t exceptionally important.” He did not respond for comment.

The White House and a representative of Musk’s Department of Government Efficiency did not return requests for comment.

A spokesperson for the Treasury Department declined to comment.

The departure of Lebryk, which was reported earlier by The Washington Post, and the potential for interference with the nation’s payment systems comes at a precarious moment for the U.S. economy. The Treasury Department had to begin using so-called extraordinary measures last week to prevent a government default after a suspension of the debt limit expired. The ability to use those accounting tools could expire as soon as this summer, and it will be critical for the department to accurately track federal expenditures.

Musk has told senior administration officials that he believes the federal government is sending out hundreds of billions to people who either do not exist or are fraudsters, according to people familiar with his remarks. The Government Accountability Office estimated in a report that the government made $236 billion in improper payments — three-quarters of which were overpayments — across 71 federal programs during the 2023 fiscal year.

Musk has been fixated on the Treasury system as a key to cutting federal spending. Representatives from his government efficiency initiative began asking Lebryk about source code information related to the nation’s payment system during the presidential transition in December, according to three people familiar with the conversations.

Lebryk raised the request to Treasury officials at the time, noting that it was the type of proprietary information that should not be shared with people who did not work for the federal government. Members of the departing Biden administration were alarmed by the request, according to people familiar with their thinking. The people making the requests were on the Trump landing team at the Treasury Department, according to a current White House official.

The inquiries into the Treasury Department’s payment processes have been led by the Musk allies Baris Akis and Tom Krause. Akis, a relative newcomer to Musk’s circle, is a venture capitalist.