Connecticut insurance regulators are still waiting — one week after a suggested deadline — for insurers to file proposed rates on health plans they intend to sell on the state's public exchange later this year.

All health insurance plans are regulated by the state Insurance Department, which has the authority to approve, modify or deny prices depending on whether they are justified by actuarial science.

In a typical year, insurers file rates in the summer for health plans that take effect the following calendar year. This year, the introduction of new public exchanges by the Affordable Care Act has moved the process earlier.

The Insurance Department wanted insurers to file rates by April 30, a week ago, for any health plan that would be sold on the public exchange. April 30, however, was a guideline, not a firm deadline, department spokeswoman Donna Tommelleo said.

The firm deadline comes at the end of July, when the state's public exchange, Access Health CT, must report to federal health officials all of the health plans that will be available to customers starting Oct. 1. Until then, it is a relative poker game in which no health insurer wants to show their hand first, several people familiar with the process have said.

"We're expecting it to be a busy month," Tommelleo said of May.

Some government snags delayed the process a bit, said Kevin Counihan, CEO of Access Health CT.

"I think you have to look at this a bit nationally … the only states that I'm aware of that have received rates are Vermont, Rhode Island and Maryland," Counihan said. "I think that all the health plans are challenged in part by the complexity of the rules, and sometimes the complexity of the guidelines provided by CMS [the federal Centers for Medicare and Medicaid Services]."

The health exchanges and insurance companies are trying to abide by rules that are evolving. And health plans sold on the exchange must adhere to very specific requirements about the benefits they provide and their "actuarial value," which is an assessment of how much a customer will pay for medical bills if you factor in deductibles and copays.

A federal actuarial calculator, released earlier this year, had glitches early on, and it is the mechanism upon which insurers must base the value of their plans, Counihan said. Any plan sold on a public exchange has a rating, named for a precious metal, to illustrate its actuarial value. A bronze plan means the insurer pays 60 percent of expenses, silver is 70 percent, gold is 80 percent and platinum is 90 percent.

"That calculator was released in late winter … I think it was March," Counihan said. "It turned out that when states and carriers started using it, they found out that it had a number of bugs. So, for example, you could raise the deductible and the actuarial value or richness of the plan would go up. Now, obviously that makes no sense. If you're cost shifting more, the actuarial value would go down."

The Centers for Medicare and Medicaid Services fixed the calculator, though some problems remained, Counihan said. Aetna confirmed Monday that it has been waiting for final guidance regarding the actuarial value of standard plans before it can proceed.

Separately, some insurers said the computer system used for filing rates — known by the acronym SERFF — was not working efficiently. However, neither the state Insurance Department nor the National Association of Insurance Commissioners, which oversees use of the SERFF system, noticed any problems with the system.

All around, the process is new and most agree that some delays are to be expected.

"There is a ton of work and resources being poured into getting this right from the plans' perspective," said Keith Stover, a lobbyist and spokesman for the Connecticut Association of Health Plans, a trade group for the health insurers.

As Counihan puts it, "These are very complex calculations and guidelines that the carriers have to abide by with sometimes incomplete and contradictory information."

In January, nine health insurers wrote non-binding letters that they intend to offer either medical insurance or dental coverage on a state health exchange. That list included Aetna, Anthem Blue Cross and Blue Shield in Connecticut, ConnectiCare, HealthyCT and UnitedHealthcare. Counihan said UnitedHealthcare notified him last week that they will not be taking part in the exchange. Cigna Corp. is not participating in Connecticut's health exchange.

Insurers were relatively mum on the issue Monday, with both UnitedHealth Group and Anthem Blue Cross and Blue Shield in Connecticut declining to comment.

Ken Lalime, the CEO of the new health insurance co-op HealthyCT, said his organization filed its rates late Friday.

"I think there's some internal process that obviously has to take place before they push them up," Lalime said, referring to the rates that are publicly posted on the Insurance Department's website.

"They encouraged us to file as early as possible, all of us, and we got ours in. It was late Friday afternoon, but we did get it in," Lalime said.