Already hit with cost increases to cover minor Obamacare demands, businesses are boosting employee payments through higher insurance premiums and doctor visit co-pays in advance of the bulk of the health reform law's rules taking effect Jan. 1.

A sweeping survey of several hundred U.S. businesses by the International Foundation of Employee Benefit Plans found that their costs have already jumped because of a rule requiring them to cover employees' children up to age 26.

To prepare for the full impact of Obamacare, said the foundation, employers are implementing "diverse cost-management initiatives." Some 43 percent are boosting premiums, 34 percent are increasing employee dependent coverage costs, and 31 percent are raising co-pays or "out-of-pocket limits."

The survey also found that 16 percent of smaller firms are adjusting the hours of workers to avoid the mandate that employers with 50 full-time workers offer health insurance or pay a fine. And a few are considering cutting spousal coverage.

But the survey found good news for Obamacare's supporters as 94 percent of organizations and businesses that already offer their employees health insurance will continue to do so, even if it is more expensive to employees. And a majority estimate that their health care costs will rise less than 5 percent.

The survey challenges Obamacare opponents who have been warning that premiums will jump 100 percent and that smaller firms will radically change their employee structure to get under the floor of 50 full-time employees.