Treasury Secretary Scott Bessent gave representatives of the so-called Department of Government Efficiency full access to the federal payment system late on Friday, according to three people familiar with the change, handing Elon Musk and the team he is leading a powerful tool to monitor and potentially limit government spending.

The new authority follows a standoff this week with a top Treasury official who had resisted allowing Mr. Musk’s lieutenants into the department’s payment system, which sends out money on behalf of the entire federal government. The official, a career civil servant named David Lebryk, was put on leave and then suddenly retired on Friday after the dispute, according to people familiar with his exit.

The system could give the Trump administration another mechanism to attempt to unilaterally restrict disbursement of money approved for specific purposes by Congress, a push that has faced legal roadblocks.

Mr. Musk, who has been given wide latitude by President Trump to find ways to slash government spending, has recently fixated on Treasury’s payment processes, criticizing the department in a social media post on Saturday for not rejecting more payments as fraudulent or improper.

It is not clear whether the team led by Mr. Musk, the world’s wealthiest man, has blocked any payments since gaining access to the system.

The Department of Government Efficiency, or DOGE, is not a government department, but a team within the administration. It was put together at Mr. Trump’s direction by Mr. Musk to fan out across federal agencies seeking ways to cut spending, reduce the size of the federal work force and bring more efficiency to the bureaucracy. Most of those working on the initiative were recruited by Mr. Musk and his aides.

Similar DOGE teams have begun demanding access to data and systems at other federal agencies, but none of those agencies control the flow of money in the way the Treasury Department does.

Mr. Bessent granted access to the payments system to a handful of staff members affiliated with DOGE, including Tom Krause, the chief executive of a Silicon Valley company, Cloud Software Group, according to one of the people familiar with the change. Access to the system has historically been closely held because it includes sensitive personal information about the millions of Americans who receive Social Security checks, tax refunds and other payments from the federal government.

A Treasury Department spokesman, a spokeswoman for DOGE and the White House did not immediately respond to requests for comment.

In a process typically run by civil servants, the Treasury Department carries out payments submitted by agencies across the government, disbursing more than $5 trillion in fiscal year 2023.

Former officials said the onus was on individual agencies to ensure their payments are proper, not the relatively small staff at the Treasury Department, which is responsible for making more than one billion payments per year.

Mr. Lebryk, the career Treasury official who retired on Friday, had resisted requests from members of Mr. Trump’s transition team for access to the data last month. After Mr. Trump took office, the White House indicated that he should be removed from the job and, according to a person familiar with the matter, Mr. Bessent suggested putting him on leave.

Democrats raised alarm this week that the Trump administration and Mr. Bessent, who was just confirmed by the Senate this week, were compromising the federal government’s payments system.

“To put it bluntly, these payment systems simply cannot fail, and any politically motivated meddling in them risks severe damage to our country and the economy,” Senator Ron Wyden of Oregon, the top Democrat on the Senate Finance Committee, wrote in a letter to Mr. Bessent on Friday. “I can think of no good reason why political operators who have demonstrated a blatant disregard for the law would need access to these sensitive, mission-critical systems.”

Mr. Wyden followed up on Saturday to express concern that access to the payment system had already been granted and pointed to Mr. Musk’s potential conflicts of interest.

“Social Security and Medicare benefits, grants, payments to government contractors, including those that compete directly with Musk’s own companies. All of it,” he wrote on social media.

During the transition, Mr. Musk vocally opposed Mr. Bessent being picked as Mr. Trump’s Treasury secretary. Mr. Musk, then just an empowered adviser to Mr. Trump, went public with his opinion that he preferred Howard Lutnick, a Wall Street executive, for the role because Mr. Bessent was “a business-as-usual choice.” Mr. Lutnick became Mr. Trump’s choice for Commerce secretary.