If the House wins the suit pending in federal court in Washington, D.C., and forces the executive branch to stop making the cost-sharing reduction payments to insurers, those insurers face a "very tricky" situation said Larry Levitt, senior vice president at the Kaiser Family Foundation.
"Because the way the law works, the insurers have to cover cost sharing for consumers," Levitt said.
In other words, if the government stops covering customers' out-of-pocket payments, insurers will "have to eat the costs," Levitt said.
Those costs would be high. Nearly 60 percent of the more than 11 million Obamacare exchange customers receive cost-sharing reductions through "silver" health plans. The customers qualify because they earn between 100 percent and 250 percent of the federal poverty level, or $11,670 to $46,680 for an individual.
The reductions are available only to customers of silver plans, which are the second-least expensive category of plans, and which cover an average of 70 percent of the overall cost of members' health benefits.
In its suit, the House noted that the Congressional Budget Office has estimated that the payments to insurers would total about $178 billion from 2014 through 2024.
"Such unconstitutional payments are estimated to exceed $3 billion in fiscal year 2014," the House suit says.
In the absence of Congressional appropriation for that money, the administration has been funding those payments out of the account that subsidizes monthly premiums for most Obamacare customers. Health and Human Services Secretary Sylvia Burwell told Congress last year that was being done on the grounds of "efficiency," the suit noted.
Timothy Jost, a Washington and Lee University law professor and leading Obamacare expert, said that without the cost-sharing reductions from the government, "Insurers would have to significantly raise premiums and might face solvency issues until they could do so."
While many insurers would raise premiums, both inside and outside the Obamacare exchanges, to cover their added costs, some issuers "could leave the market" to avoid dealing with the costs, he said.
Cost-sharing reductions are "a huge thing" for their recipients, and not having them would be a "deal breaker," Jost said.
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He noted that cost-sharing reductions can turn a silver plan's $5,000 annual deductible into just a $200 deductible.
"Even if you're paying $50 per month for your silver plan [in premiums] if you've got a $5,000 deductible, forget it, you're as good as uninsured," Jost said. Without the cost-sharing reductions, "People are simply not going to be able to afford coverage."