Elon Musk’s Department of Government Efficiency has deleted hundreds more claims from its mistake-plagued “wall of receipts,” erasing $4 billion in additional savings that the group said it had made for U.S. taxpayers.

Late Sunday night, the group erased or altered more than 1,000 contracts it had claimed to cancel, representing more than 40 percent of all the contracts listed on its site last week. The deleted items included five of the seven largest savings that it had claimed credit for just last week. At the same time, the group added about 1,000 additional canceled contracts, worth smaller total savings.

It was the second time in a week that DOGE had deleted some of its greatest claims of success. Early last week, it erased all five of the largest savings it had claimed when the wall of receipts, which is what the group is calling its list of canceled contracts, was originally posted on Feb. 19.

Since that first posting, the total amount of savings that the initiative has claimed from cutting contracts has steadily declined, from $16 billion at first to less than $9 billion now.

The “wall” shows only some of the cuts Mr. Musk has imposed on government, making it difficult to assess the claim that his initiative has saved taxpayers more than $100 billion. But the site is the only place where the group has given a detailed public accounting of its work, providing a rare look at its basic competence and familiarity with government data.

Contracting and budget experts say that look has been worrisome.

From its start, the list has been full of errors: claims that confused billions with millions, triple-counted the same cancellation, or claimed credit for contracts that had ended years or even decades before. Contracting experts said these mistakes raised questions about DOGE’s basic understanding of the federal government, at a time when Mr. Musk’s group is attempting to rapidly overhaul it.

“Overall, there’s a certain randomness to it,” said Jessica Riedl, a senior fellow at the Manhattan Institute, a conservative think tank. “It seems like DOGE had certain agencies pull together some random lists of contracts that may or may not currently exist anyway, and then, without checking the data very well, uploaded it onto a website and summed up the amounts. It doesn’t seem to be centrally coordinated.”

Mr. Musk’s group and the White House did not respond to requests for comment about the new deletions sent on Monday morning. Since news media outlets began to point out errors in the list, the group has added language on its website that shifts the blame onto individual federal agencies — saying the dollar figures on its site “originate directly from agency contracting officials.”

Among the largest claims that disappeared:

• A $1.9 billion savings that the group said it had achieved by canceling an Internal Revenue Service contract for tech help. Before Sunday night, this had been the biggest single savings on the site. But The New York Times reported that the contract was actually canceled in November, while Joseph R. Biden Jr. was president.

• A $149 million savings attributed to canceling a contract to provide three administrative assistants at the Department of Health and Human Services. The entry on the site last week contained numerous errors, including a link to a different contract, with a different company, that did not involve administrative assistants or $149 million. On Sunday, after The Times mentioned this garbled entry, it disappeared.

• A $133 million savings that the group said had come from canceling a U.S. Agency for International Development contract for work in Libya. The contractor, Chemonics International, posted last year on LinkedIn that its work on that contract had already ended.

Even after the changes to the group’s website, however, some errors remained. As of Monday morning, the list still included claims that DOGE achieved $106 million in savings by canceling a pair of contracts that the Coast Guard signed for administrative help.