Selection Time

Another risk, he said, is that healthier consumers will choose HSAs, leaving an older and sicker pool behind. "Without a younger, healthier pool of people among whom to spread risk, I'd expect to see insurance premiums skyrocket among older, sicker consumers over the next few years," Pollack said.

A Good Plan for You?

Before you commit, it's a good idea to read through the list of frequently asked questions (www.opm.gov/hsa/faq.asp) posted by the federal Office of Personnel Management. Even if you work in the private sector or are shopping for an individual policy, the questions should prepare you for a talk with your agent or your employer's benefits staff. This is especially important for individual policy buyers, since they'll likely be dealing with salesmen who may biased toward their own product.

Here are some reasons you may find an HSA tempting:

• You own the money in the account even if you retire or change plans or employers.

• Tax-free withdrawals may be made for expenses such as prescription drugs, a doctor visit for a sinus infection, setting a broken arm and physical therapy prescribed by a doctor. (See the IRS list at www.irs.gov/publications/p502/ar02.html#d0e516.)

• Unused funds and any interest they've earned can be carried over, without limit, from year to year. (You can even spend set-asides on nonmedical expenses. But do that before age 65, and you'll pay income tax on the funds used plus a 10 percent penalty.)

• Contributions to an HSA by your employer, your insurer or yourself are not considered income on which you owe federal taxes. If your employer doesn't allow pretax payroll deductions for your HSA, you may choose to fund your account with after-tax dollars and then claim an offsetting deduction when you file your annual tax return.

Some benefits experts, like Greg Scandlen, a senior fellow at the nonprofit National Center for Health Policy Analysis, say all consumers can realize savings with HSAs, because of their tax advantages and the lower premiums that come with high-deductible insurance. But others worry that people who don't adequately fund an HSA will find it hard to meet the deductible and even harder to afford the coinsurance bills they will face before reaching the annual cap on-out-of-pocket obligations.

Break your leg on a ski trip, for example, and your HSA could be quickly drained by two surgeries and months of physical therapy. That could be the case even if you negotiate the fees and services tied to surgery, anesthesia and other services -- a habit it may be prudent to cultivate. But shopping around for quality care can be difficult -- especially when it involves emergency care or other unanticipated needs.

On top of that, deposits into the account may be spread out over the entire year. As a result, if you incur major expenses in February, you may have to pay out of pocket, or out of credit card, until the plan reimburses you.

"These are risk-oriented plans," said the Kaiser Family Foundation's Claxton. "Keeping yourself healthy [by doing things] such as keeping weight down and getting exercise means you're less likely to have to shell out for heart surgery or diabetes medicines down the road. But the plans are not at all sympathetic to accidents, and that's an expense you just can't predict."

Planning Ahead

But there are some predictions you can make, and many firms, including Aetna, are offering online calculators to help you track past expenses and predict future ones. Aetna, together with the Financial Planning Association, a trade association for financial planners, has put together some online decision-making tools that can help you sort through your options.

For example, the site has an excellent list of options you should look for in your plan (www.planforyourhealth.com/careers_rank.cfm). But bear in mind that the information Aetna presents is likely to put HSAs in a favorable light.•

Francesca Lunzer Kritz wrote about health insurance options for last year's special Open Season issue of the Health section.