By Cameron Huddleston, Former Online Editor September 23, 2009 Fall is here, and that means open-enrollment season is upon us. Those of you who have employers that provide benefits are given the chance to review your insurance options, such as health, dental and disability, and switch plans during this period. You'll also get the change to sign up for a flexible spending account.If you aren't taking advantage of this valuable account, listen up: You can save 35% or more on out-of-pocket medical costs and dependent care by using an FSA.Contributions to an FSA come out of your paycheck before taxes -- so you don't have to pay taxes on that portion of your income. Then you can use the money tax-free to pay for such things as health-care deductibles, co-payments, dental work, childcare and more (see 25 Ways to Spend Your Flex Account Money.)For example, put the maximum $5,000 into a plan to pay childcare bills, and you would save almost $2,000 in taxes (assuming a 25% federal bracket, 5% state bracket and 7.65% Social Security tax.) It's especially important to set aside money in an FSA for health-care expenses because more employers are asking employees to share the burden of rising health insurance costs by paying higher deductibles and co-pays (see Employer-Sponsored Health Care Costs Rising.) Another reason to take full advantage of your flex account now : One of the ways being proposed to help pay for health care reform is to slap a limit of $2,000 to $2,500 after 2010 on what could be set aside tax-free annually. Right now, there is no limit written into the law (although companies often impose a cap of $4,000 to $5,000 a year). Use our calculator to find out how much you should put in your FSA.