The U.S. economy probably added close to a million fewer jobs in 2024 and early 2025 than previously reported, the latest sign that the labor market, until recently a bright spot in the economy, may be weaker than it initially appeared.

The revised data was released by the Bureau of Labor Statistics as part of a longstanding annual process known as benchmarking. But the big downward adjustment comes at an awkward moment for the agency, just weeks after President Trump fired its top official following a separate set of negative revisions last month.

The data released on Tuesday showed that employers added 911,000 fewer jobs in the 12 months through March than had been indicated in the monthly payroll figures. That implies the economy added only about 850,000 jobs during that time — half as many as previously reported.

The report doesn’t directly affect the period since March. But the scale of the overestimate has led many economists to conclude that more recent job gains have probably also been overstated. That could concern policymakers at the Federal Reserve, who have been watching closely for signs that the labor market is losing momentum.

In a speech in Miami last month, Christopher J. Waller, a Fed governor, cited the forthcoming benchmark revision as one reason that he supported cutting interest rates at the central bank’s meeting next week. The case has only grown stronger since then: On Friday, the Bureau of Labor Statistics reported that employers added just 22,000 jobs in August, and that the unemployment rate had edged up to 4.3 percent, its highest level in nearly four years.

The revision announced on Tuesday is preliminary and won’t be incorporated into the government’s official jobs figures until complete data is available early next year.