Medicare Supplement (Medigap) Underwriting: What It Is and How It Works

What Medigap medical underwriting actually is

Medical underwriting is the process an insurance company uses to evaluate your health history and any pre-existing conditions before issuing a Medicare Supplement (Medigap) policy. Based on that review, the insurer can approve your application, charge you a higher premium, attach a waiting period for pre-existing conditions, or deny coverage entirely.

Underwriting typically involves a health questionnaire and may include a review of prescription-drug records and your Medicare claims history. Each insurer sets its own underwriting guidelines, so an answer that disqualifies you with one company may be acceptable to another. Because of this, approval and pricing vary by insurer and by state.

Underwriting matters because Medigap policies are medically underwritten in most situations once your initial protected window closes. That makes timing your application one of the most consequential decisions in choosing supplemental coverage.

When underwriting does NOT apply: your 6-month Open Enrollment window

Under federal law, you get a one-time, 6-month Medigap Open Enrollment Period that begins the first month you are both age 65 or older and enrolled in Medicare Part B. This window does not repeat each year.

During these 6 months, insurers cannot use medical underwriting to reject your application, cannot charge you more because of pre-existing health problems, and must sell you any Medigap policy they offer in your state. This is the single best time to buy if you have any health conditions.

• Starts automatically — you do not apply for it
• Lasts exactly 6 months and cannot be restarted or extended in most cases
• Guarantees access to any Medigap plan the insurer sells in your state
• Missing it is the most common reason people later face underwriting

Guaranteed-issue rights: federal protections outside Open Enrollment

Even after your Open Enrollment Period ends, certain situations trigger federal 'guaranteed-issue rights' (also called Medigap protections). In these cases an insurer cannot deny you, cannot charge more for health reasons, and cannot impose a pre-existing condition waiting period. You generally have 63 days to apply, and you must give the company proof of your qualifying situation.

Guaranteed-issue rights typically apply to a limited set of standardized plans rather than every plan on the market, and the exact plans available depend on federal rules and your state.

• A Medicare Advantage plan leaves Medicare, stops serving your area, or you move out of its service area
• Employer or union retiree coverage that supplements Medicare is ending
• A 'trial right': you joined Medicare Advantage at 65 for the first time and switch back to Original Medicare within 12 months
• Your Medigap insurer goes bankrupt or you lose the policy through no fault of your own
• Apply within the 63-day window — usually counted from when prior coverage ends

Pre-existing conditions and the look-back waiting period

Separate from approval, federal law lets a Medigap insurer impose a waiting period of up to 6 months before it covers care related to a pre-existing condition. This 'look-back' can apply even during your Open Enrollment Period.

However, if you had at least 6 months of continuous prior 'creditable coverage' before you applied, the insurer must shorten or eliminate that waiting period. Most prior health coverage — including employer plans and Original Medicare — counts as creditable, which is why avoiding gaps in coverage protects you.

Why passing underwriting can be worth it

Medigap policies help pay the out-of-pocket costs Original Medicare leaves to you. For 2026, those gaps include the Part A hospital deductible of $1,736 per benefit period and the 20% coinsurance you owe for most Part B services after meeting the $283 annual Part B deductible (CMS figures).

What each Medigap plan pays toward these gaps varies by plan letter and is standardized by the federal government, but premiums and underwriting outcomes vary by insurer and state. Compare both the coverage and the price before applying.

If you are outside a protected window and have health conditions, an independent agent or your State Health Insurance Assistance Program (SHIP) can help you identify which insurers' underwriting you are most likely to pass.