But states could vary widely. States like New Jersey, which already has many of the PPACA provisions in place that highly regulate insurance, will see less of an impact than other states — with some premiums dropping by as much as 25 percent, the firm said.

In more "traditional" states that don't have as much regulation, some individuals could see an increase of 50 to 60 percent.

In many cases, that's because individuals who are choosing low coverage policies will have to upgrade to policies that must offer at least a certain level of coverage under PPACA.

But most people with huge premium increases should get help from subsidies from the federal government. Milliman also found that 40 percent to 60 percent of people in the individual market will be eligible for subsidies to help offset the cost of insurance.

Just last week, California unveiled sample rates for health plans under its state exchange. For the most part, California's rates emerged as less expensive than expected, with supporters of the law claiming it was a "home run" for consumers. Some critics, though, called out Covered California, the agency tasked with setting up the exchange, for making an apples-to-oranges comparison.