If there’s one thing many small-business owners can take away from the Supreme Court’s decision to uphold the Affordable Care Act, it’s a little more certainty.

Consider Richard Balka, owner of The Home Rubber Company L.P. in Trenton, N.J., which offers health insurance to its 37 employees. He said Thursday that he was pleased that the Supreme Court upheld the provision that ensures people can get coverage despite having a pre-existing health condition.

“That freed my conscience in the event I have to stop offering health care to my employees,” he said. “If I had dropped it, anyone who either had a pre-existing condition or family member with a pre-existing condition would be in a horrible position.”

The Supreme Court voted 5-4 to uphold a provision requiring taxpayers to carry health insurance or pay a penalty. The majority opinion, by Chief Justice John Roberts, found that the penalty effectively functioned as a tax, by increasing the income taxes of those without qualifying insurance, and was therefore justified under Congress’ constitutional power to levy taxes and provide for the general welfare.

Of course, the decision still leaves small-business owners wondering how the law will impact the cost of health care.

Some expect the law to lead to lower health-care premiums, with the cost of health care spread among a larger pool of insured Americans. Others, though, predict that premiums will rise and worry that they’ll be forced to provide coverage that they can’t afford, starting in 2014, when many of the law’s key provisions take effect.

Even Mr. Balka said he is still concerned that health exchanges, expected to roll out at the state level come 2014, “may not go far enough” to curb the cost of providing insurance to employees.

Premiums at the rubber-manufacturing facility have increased between 8% and 20% each year in the last 15 years.

Makini Howell, owner of Plum Bistro, a group of four vegan restaurants in Seattle, had no reservations about Thursday’s ruling. “It’s a good thing it wasn’t shot down because we wouldn’t be able to offer coverage,” she said.

Plum Bistro began offering insurance to its eight full-time employees about three months ago. Ms. Howell credits a small-business tax break that rolled out as part of the law as one reason for her ability to offer insurance. She is also looking forward to the health exchanges, which, she believes, could “level the playing field for us.”

Some small-business owners say the law doesn’t affect them now, but voiced concern about how provisions of the law might impact their plans to add to their payroll as they grow.

Elie D. Ashery, president of Gold Lasso Inc., a 10-year-old Gaithersburg, Md., marketing firm, currently has 25 employees and is growing fast, he said. He thinks the law will only push premiums higher.

Though the firm offers health insurance, its premiums have been rising by 26% on average annually over the past four years, he added.

If the firm’s headcount rises above 50, then it might turn out to be less costly to pay a penalty than continue to provide health insurance. “It’s an option I’d have to consider,” he said.