Most employees still in the dark about health care reform

FORTUNE — With open enrollment season almost upon us, you might think most big companies have already explained to their workers the changes that will arise from the Patient Protection and Affordable Care Act. After all, the law has been around for well over two years, and the original deadline for telling employees how it would affect them was way back in March, then got extended until October 1.

Even so, when insurer Aflac conducted its annual open-enrollment survey this year, the researchers got a surprise: Not only have about 70% of employees heard nothing about how their health benefits will be affected, but only 9% of companies said they are “very prepared” to start making the changes the law requires.

Why the delays? “Part of it is that the practical details have been evolving, with new information coming out of Washington and the state exchanges all the time,” observes Audrey Boone Tillman, an Aflac executive vice president. “So employers hesitate to dive too deep into explaining things that are still changing.”

Another holdup, she adds, may be that “under the Affordable Care Act, some companies’ benefit plans won’t provide the same level of coverage as they did before, and there is a real reluctance to deliver bad news.”

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That’s understandable, considering that so many U.S. employers have already been the bearers of bad tidings in this area. Average annual worker contributions for family health insurance coverage have gone up a whopping 89% since 2003. More than half (53%) of American companies have shifted to higher deductible health plans in the past few years.

For many employees, it’s been a tough adjustment: 83% of employees Aflac surveyed say they can afford $1,000 or less in annual deductible costs. About half say that $25 per month is the maximum increase in premiums that they can afford, and 40% say they’ll have to cut other living expenses if health care premiums go up at all. Yet 69% of employers in Aflac’s study say they believe the Affordable Care Act will drive up workers’ out-of-pocket costs — not an announcement that anyone is eager to make.

Employers might be quicker to communicate the coming changes to the health care landscape if they understood them better themselves. “The complexity of the law’s provisions is a major factor” in putting off telling employees how they’ll be affected, Tillman notes.

To take just one example of how complex things can get: The law requires companies to offer “affordable” coverage to all full-time employees, which sounds straightforward enough. But determining who is a full-time employee — defined as a person who works 30 hours a week or more — obliges companies to use a mind-bendingly complicated formula.

“This has an especially big impact on businesses like retailers and hotels that have a lot of seasonal employees, or people who work variable hours,” says Joann Hall Swenson, a partner in benefits consulting giant Aon Hewitt. “It’s not enough just to label someone ‘part-time’ or ‘full-time.’ You have to apply the formula accurately to each worker” — and there are stiff penalties for getting it wrong.

At the other, more enviable, end of the complexity scale, notes Aon Hewitt health and benefits practice leader Michael Phillips, are big companies whose current benefits offerings will be virtually unchanged by the new law. “The challenge is, how much is it necessary to communicate?” Phillips says. “Many of our clients don’t want to confuse their employees by explaining changes that don’t apply to them.”

For employees, then, radio silence from human resources could mean nothing much is changing — or everything is, and the people upstairs just haven’t said so yet. In the Aflac survey, 60% of employees polled admit they’ve made no effort on their own to look into whether, or how, the Affordable Care Act will affect them, despite a wealth of detailed, up-to-date information readily available online from the Department of Health and Human Services and other sources.

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“The belief is, ‘Someone will tell me what I need to know,’” says Aflac’s Boone Tillman. Aflac has set up a website, dubbed the Health Care Reform Communications Toolkit, to walk employers through the process of getting the word out.

Tricky as it may be right now to figure out how the new law will play out, things should be simpler, or at least clearer, by the time the 2014 open-enrollment season rolls around. “This is the most complicated year,” says Swenson at Aon Hewitt. “After this, there will be far fewer decisions to make among unfamiliar options, and more guidance available.”

Boone Tillman agrees, but hopes employees will take the time to weigh their options carefully right now. “Ninety percent of workers just go on autopilot and select the same benefits plan they had the year before, but this time around that could lead to some very costly gaps in coverage,” she says. “It’s definitely not the year to go on autopilot.”

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