WASHINGTON (Reuters) - Annual benchmark revisions to U.S. nonfarm payrolls are likely to show the economy added about 668,000 fewer jobs in the 12 months through March, instead of the initially estimated 818,000, updated data suggested on Thursday.

The Labor Department's Bureau of Labor Statistics updated the Quarterly Census of Employment and Wages (QCEW) data for the first quarter from which it based the payrolls benchmark revision. Once a year, the BLS compares its nonfarm payrolls data, based on monthly surveys of a sample of employers, with a much more complete database of unemployment insurance tax records.

A final benchmark revision will be released in February along with the BLS' report on employment for January. Government statisticians will use the final benchmark count to revise payroll data for months both prior to and after March.

"Today's revision extends the systematic pattern of upward revision to initial QCEW estimates seen since the pandemic," said Jonathan Millar, a senior economist at Barclays. "This, in part, reflects low initial response rates for the QCEW, which have drifted downward in recent years."