As you get older, your chances of having a medical condition of some kind increases: according to the Centers for Medicare & Medicaid Services (CMS), up to 86% of older Americans between age 55 and 64 have a pre-existing medical condition. You usually hear the term “pre-existing condition” when it comes to medical underwriting, a process where insurance companies take your health status and medical history into consideration before deciding whether to insure you and how much to charge you for coverage.

So, what exactly is a pre-existing condition, and more importantly, how does it affect the cost of Medicare coverage?

What is a pre-existing condition?

According to CMS, a pre-existing condition is a “health condition that exists before someone applies for or enrolls in a new health insurance policy.”

This may include commonplace conditions, such as hypertension, asthma, or diabetes. It may also include cancer, heart disease, or mental health illnesses like depression or anxiety. According to the Kaiser Family Foundation, some insurers may also take into consideration health issues you might not normally think of, such as kidney stones, allergies, migraines, or acne.

If an insurance company is allowed to use underwriting, your health status could still affect you even if the insurer doesn’t reject your application outright. You might have to pay higher premiums, or the insurance company might agree to insure you, but exclude your pre-existing condition from its coverage (meaning you’d have to cover any costs related to treating your pre-existing condition). You might have a higher deductible and pay more out of pocket before benefits start.

Does a pre-existing condition affect my cost for Medicare coverage?

If you have a pre-existing condition, or multiple pre-existing health conditions, this generally shouldn’t affect your Medicare costs. As long as you meet the eligibility requirements for Original Medicare, the cost of Medicare coverage such as premiums, copayments, coinsurance, and deductibles shouldn’t be affected because of your health issues, disabilities, or pre-existing conditions.

If you’re eligible for Medicare Part D prescription drug coverage, your plan should cover medications to treat your pre-existing condition (as long as those medications are normally covered under Part D). You should check the plan’s formulary, or list of prescription drugs, to be sure your specific medications are covered. Also, keep in mind that formularies may change at any time, and the Medicare plan will notify you if necessary.

There are a few situations where having a pre-existing condition may affect your Medicare costs or coverage. For example, Medicare Advantage plans may deny you coverage if you have end-stage renal disease (ESRD). However, there are exceptions in which Medicare Advantage plan enrollment is possible for individuals with ESRD.

Having a pre-existing condition may also affect your Medicare costs is if you’re enrolling in a Medicare Supplement (Medigap) plan outside of your Medicare Supplement Open Enrollment Period. This is the six-month window when you have a guaranteed-issue right to any Medicare Supplement plan offered in your service area, regardless of your medical history or pre-existing conditions. You can’t be denied coverage or charged higher premiums during this time because of health. However, once your Medicare Supplement Open Enrollment Period is over, insurance companies can use medical underwriting, and the cost of your Medicare coverage could go up unless you have another situation where you have a guaranteed-issue right.

Note that even during your Medicare Supplement Open Enrollment Period, the insurer may make you wait up to six months before covering any pre-existing conditions that were diagnosed or treated in the six months before your Medicare Supplement policy starts. After this “pre-existing condition waiting period” is over, the plan will cover any Medicare costs related to your pre-existing condition(s).

Oftentimes, a good way to keep the cost of your Medicare coverage in check is by comparing plan options to find coverage that fits your budget. Click on the Get Quotes button on this page to start comparing Medicare plans for free.