If your employer allows you to sock away some money in a flexible spending account, it can save you big bucks on your income taxes as long as you have a clear understanding of what the IRS considers to be “qualifying expenses.”

If you use a health savings account in conjunction with a high-deductible health insurance plan, you can save money by spending your HSA funds on these qualifying expenses because your HSA funds will have been saved before you paid taxes on them.

Take a look at the master list of FSA qualifying expenses from the IRS, but realize that it’s the translation of the list, and what’s missing from the list, that will best help you maximize your use of the funds you have set aside, thus saving yourself the most tax money.

Below are some examples of expenses you may not realize are qualifying medical expenses.

But beware: beginning in the tax year 2011, beginning in the tax year 2011, over-the-counter drugs were no longer eligible to be reimbursable by FSAs or HSAs unless a healthcare provider writes a prescription for them. You need to learn about (and a tactic for working around it) non-qualifying medical expenses.

If you are coming up on the end of the year and have extra FSA money to spend, then ask your practitioner to write your next year’s prescriptions for whatever drugs you take on a regular basis, including birth control pills, blood pressure medicine, even lifestyle drugs like Viagra.

Of course, if you do pay to purchase those drugs in one year, don’t include them in your estimate of expenses in the next year.

If you are coming up on the end of your FSA year, it might be a good time to talk to your practitioner about quitting smoking, losing weight, or if necessary, checking yourself into a rehab center. Just be sure to write the necessary checks during the year you want to apply those expenses to your FSA.

For example, if you get involved in a weight loss program (Weight Watchers, Jenny Craig, others), or if you work with a weight loss trainer under the auspices of your healthcare provider, and you pay for those services aside from your insurance, then they may qualify.

You’ll need to subtract from those qualified expenses the costs of food, or any expenses that are simply substituted for something else you might have needed prior to the weight loss activity.

However, there may be some preventive or screening tests that aren’t on that list that you may want because of pre-existing conditions or family history. Co-pays or the total cost for body scans or colonoscopies or others will be reimbursable through your FSA or HSA.

If you’re getting close to the end of the year, and have extra FSA money to spend, ask your healthcare provider which tests you can move into the current year so they can be paid for using your FSA set-aside money.

Railings, support bars, modifying hallways, doors or stairways, building an entry ramp or any other modification—as long as it needed to be done to improve your access to parts of your home because of physical/medical challenges, you can be reimbursed by the FSA or HSA.

The IRS provides guidelines, and a worksheet to help you determine whether your home improvement expenses qualify.

Keep the receipts, make a note about what the batteries are used for to be sure you distinguish them from any other battery purchase that may not qualify.

If it’s the end of the year and you need to use up FSA money, then buy some extra batteries for those health or medical devices.

Again, be careful. The IRS is very specific about the rules that must be followed.

Consider attending a conference that addresses your medical interests. The IRS will allow you to use HSA and FSA funds to pay for conference admission, although it will not allow you to use those funds for your transportation, lodging or meals.

A reminder that your actual out-of-pocket, reimbursable costs will not be the total cost of these events or products; rather they will be anything that is not covered by your health insurance.

Be diligent about keeping a mileage log and your receipts to back up any reimbursements you hope to achieve.

If you are coming close to the end of the tax year, consider purchasing extra sets of contact lenses, or an extra pair of glasses, if you need to use up funds.

To document your need for a wig, ask your practitioner to write you a letter or include the advice in his or her healthcare provider’s notes. Include a copy of the letter or notes along with your reimbursement submission, but be sure to keep an extra copy with your own records.