"We have distilled several findings that we would ask you to carefully consider as you make your final rate decisions," Counihan wrote. "We ask that you consider these findings as you work to finalize rates for the 2016 plan year."
"We appreciate all that you and your staff do, and have the opportunity to do, to maintain affordability for consumers, while ensuring issuer solvency."
Read what Kevin Counihan told insurance commissioners here: July 21 letter
Counihan argued that newly enrolled Obamacare customers are healthier than the first wave of enrollees, and that insurers' "risk pools" are expected to get healthier, leading to lower average health claims per customer in plans.
And he wrote that the increase in the Obamacare penalty next year as well as the fact that people had to start paying fines for not having health coverage this past tax filing season, "should motivate a new segment of the uninsured who may not have a high need for health care to enroll in coverage." The Obamacare penalty for not having health coverage in 2014 was up to 1 percent of household income. It rose to the higher of $325 or 2 percent of income this year, and will jump again to the higher of $695 or 2.5 percent of income in 2016.
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Another factor that Counihan asked insurance commissioners to take into account was recent data showing that medical cost increases "remained moderate through the end of 2014 and into early 2015, even accounting for rapid growth in pharmaceutical costs."
He also cited two programs designed to lessen the costs Obamacare insurers are incurring from covering their customers, many of whom were previously uninsured. The federal Centers for Medicare and Medicaid Services recently announced that one of those programs would cover a larger share of costs from customers than originally planned.
Counihan added that "many states have found the use of public hearings helpful in rate evaluations."
A U.S. Health and Human Services Department official disputed the suggestion that Counihan wrote the letter out of fear that rates would rise too much next year. HealthCare.gov is run by the Centers for Medicare and Medicaid Services, which is a division of HHS.
"Based on preliminary findings for the coming year, we are confident that, overall, consumers will retain access to a wide range of affordable options in 2016," said the official, who spoke on the condition of anonymity. The official cited a projection by insurance companies that most Obamacare customers will be enrolled in plans with proposed rate hikes of less than 10 percent.
"The purpose of the letter is to reinforce the importance of active rate review and evaluation as part of [the Centers for Medicare and Medicaid Services'] going responsibilities in this area," the official said. "Active rate review can be extremely beneficial to consumers—in 2013, consumers saved approximately $1 billion and rates dropped by 8 percent in the individual market and 11 percent in the small group market thanks to rate review."