Health insurance deductibles and co-payments, plus uncovered items like your child's braces, can put a dent on your bank account.

That's why flexible spending and health savings accounts, where you put money away tax-free to pay for out-of-pocket health-care expenses, generally are good ideas. What's better, the saved money from an FSA and an HSA lowers your reported taxable income, just like contributing to a retirement account. Which is the best for you, though, an FSA or an HSA?

First let's look at how they are constructed. You can get into these health accounts during your employer's open enrollment period, which usually runs through December. You also can enroll if you have a "qualifying life event," such as a change in marital status, a new child, or the death of a spouse or dependent. And if you take a new job, you can sign up within 30 days.