It was barely more than a year ago, during the first ObamaCare sign-up period, when customers were stunned to learn that low-cost bronze plans carried deductibles of $5,000 or even $6,000.

By now, the maximum $6,800 bronze deductibles being proposed for 2016 plans have likely lost most of their shock value. The new sticker shock is silver plan deductibles that can reach as high as $6,500 as insurers push the envelope in finding ways to hold down premiums.

In some ways the news is better than it sounds because this type of silver plan only requires a co-payment, not full payment, for doctor visits and generic prescriptions. Amid concern about surprisingly large ObamaCare premium-hike proposals for 2016, Coordinated Care, which already offers the cheapest silver plan in Seattle, is proposing to charge 4.2% less next year for a silver plan.

The lower premium is deceptive, however, because the plan's features are changing so dramatically. This year, Coordinated Care's lowest-cost silver plan, Ambetter Balanced Care, has a $5,000 deductible, which is the maximum that a plan member has to pay out of pocket before the insurer covers all additional costs. Its proposal for 2016, which Washington state regulators must approve, has a silver plan deductible of $6,500.

Silver Side Effect

While Democrats and liberal groups raise public concerns that high deductibles may lead people to delay needed treatment, sky-high silver-plan deductibles also may produce an entirely different kind of side effect: much-higher after-subsidy premiums for ObamaCare exchange customers who choose bronze-level coverage or lower-deductible silver plans.

That's because the size of exchange subsidies depends on the price of the second-cheapest silver plan in each market. Largely because Coordinated Care is pricing not just one but two silver plans so low, the subsidy available to 30-year-olds earning 250% of the poverty level in Seattle-area King County would fall from $319 this year to $34 in 2016, if these rates are approved.

Won't Attract Young Adults

That would boost after-subsidy premiums for the cheapest bronze plan by 22% to $2,134 a year — more than three times ObamaCare's $695 individual-mandate tax penalty for going uncovered in 2016. Given that the cheapest bronze plan, also offered by Coordinated Care, has a $6,800 deductible, chances are high that young adults would pay the fine.

Coordinated Care is hardly the only insurer to offer a high-deductible silver plan. Blue Cross and Blue Shield of Texas is offering a $6,000 deductible this year in Houston, for example.

What stands out in King County is that the second-lowest-cost silver plan will only be 12% more expensive than the cheapest bronze plan, less than half of the gap that is typical nationwide.

That second-lowest-cost silver plan offered by Coordinated Care, with a $5,500 deductible and $6,500 maximum out-of-pocket cost, will cost a 30-year-old $202 a month. That's actually 10% less than the cheapest bronze policy proposed for 2016 by market leader Premera Blue Cross, which is seeking an overall 9.6% rate increase.

Larry Levitt, who directs health reform study at the Kaiser Family Foundation, explains that very-high-deductible silver plans "offer advantages for consumers with modest health expenses, providing good coverage for everyday services like visits to the doctor or the pharmacy.

Such plans, he adds, "mean higher costs, however, for people who have substantial health expenses, like those who end up needing hospital care.

Coordinated Care expects the bulk of its customers to select such plans, which may be less likely to attract people with chronic conditions. So it's possible that the company is pricing in substantially healthier members than its peers expect.

Silver plans are the most common exchange selection because customers with incomes up to 250% of the poverty level are eligible for extra subsidies that lower out-of-pocket costs.

Even with these extra cost-sharing subsidies, people earning from 201% to 250% of the poverty level would face a $4,500 deductible under the cheapest silver plan. Those with incomes from 151% to 200% of the poverty level, who get more generous cost-sharing support, would still face $1,750 deductibles.

IBD efforts to contact the company, a division of Centene , were unsuccessful. In general, insurers treat premium-pricing strategies as proprietary.