The same scene plays out in Robert DeMeola’s Midtown Manhattan office every few weeks now — not that it ever gets any easier. In walks a director or senior accountant, job offer in hand, threatening to leave for a hedge fund or big bank unless Mr. DeMeola can deliver a raise of 30 percent, sometimes more.

“It used to be once a quarter. Now it’s every month,” said Mr. DeMeola, chief operating officer of CohnReznick, a national accounting, tax and advisory firm headquartered in New York. “They expect you to negotiate.”

For much less senior workers at CohnReznick, even those with a college degree or other postsecondary education, it is another story. “We never like to lose someone good, but it’s easy to teach someone those skills, and there are others in the marketplace who want those jobs,” Mr. DeMeola said.

The very different treatment accorded employees at the very top versus those in the bottom or middle ranks has become a fact of life at corporate offices, law and accounting firms, and other white-collar bastions across the country.