If you have Medicare, you may be finding that it doesn't cover all your health costs. That's why there is Medicare supplemental insurance (Medigap). This type of health insurance pays for costs that the original Medicare program doesn't cover, and also for some costs that the original program does cover.

You can purchase a Medigap insurance policy through a private insurance company, such as AARP. There are many plans available, but by law, each company can only offer 12. Each plan offers different benefits, so you will want to take your time and research the plans before making a choice. All 12 Medigap plans offer the same basic benefits, such as paying for your hospital stay from day 61 through 150. The original Medicare plan pays the full amount for your hospital stay for up to 60 days (after you pay your deductible). From days 61 to 150, you have to pay a co-pay.

In addition, Medigap will cover the cost of 365 more days of hospital stay in your lifetime; once you have used up the 150 hospital days covered by your Medicare policy. Your benefit period starts the day you are admitted to the hospital and ends when you have been out of the hospital for 60 days in a row.

The new benefit period begins 60 days after your last discharge date from the hospital. The original Medicare plan covers 80 percent of doctor visits (after the deductible) and other medical services. Medicare covers 50 percent of mental health services and 100 percent of certain preventative services. Medigap covers all or some of your costs for these services. It pays 20 percent of amounts approved by Medicare for doctor visits and 50 percent of mental health services.

There are extra benefits offered by different Medigap plans. Review these to help you decide which plan you need. Some plans cover your Medicare deductibles for each hospital stay and for doctor visits and other medical services. Some cover skilled nursing home costs not covered by Medicare. A few of the plans will cover excess charges, which are charges not approved and paid for by Medicare. Other types of coverages available are foreign travel emergency, at-home recovery and preventative care. AARP Health Care Options offers Medicare Supplemental Insurance. Rates and plans vary depending on age and location.