Companies are focused on jittery consumer confidence, an unstable stock market, perceived obstacles to business expansion like government regulation and, above all, swings in demand for their products.

“You still need to have the business need to hire,” said Jeffery Braverman, owner of Nutsonline, an e-commerce company in Cranford, N.J., that sells nuts and dried fruit. While a $4,000 credit could offset the cost of the company’s lowest-cost health insurance plan, he said, it would not spur him to hire someone. “Business demand is what drives hiring,” he said…

For others, the math just does not add up. Roger Tung, the chief executive of Concert Pharmaceuticals, said the company, a privately held biotechnology firm with 45 employees, would save $150,000 a year from the proposed corporate payroll tax deductions.

But that is still not enough to cover the cost of hiring even one additional employee at the Lexington, Mass., company, Mr. Tung said, once benefits and other expenses besides salary are included. He can hire, he said, only when investors become confident again and the company can raise more money.