The Randstad employee confidence index decreased in January to a reading of 52.1. The 3.3-point fall from December’s reading of 55.4 is steeper than in any month-to-month comparison in 2012. The index measures workers’ confidence in their personal employment situation and optimism about the economic environment.

“Our recent findings show U.S. workers are somewhat more concerned as we head into the new year,” said Jim Link, Randstad US managing director. “Many economists and other widely cited confidence indices, such as the Conference Board’s consumer confidence index, point to the increase in payroll taxes having an effect on workers’ sentiment. It is possible this tax hike could dampen consumer confidence for the near future and our findings are clearly showing an impact on January’s numbers already.”

Fifty-three percent of employees believe there are fewer jobs available, down 7 percentage points from the previous month’s reading.

The index is based on an online survey conducted by Harris Interactive on behalf of Randstad. It surveyed 1,375 employed U.S. adults. The survey took place between Jan. 14 and Jan. 16, 2013.