Medigap Underwriting Rules: Open Enrollment, Guaranteed Issue, and Why Timing Matters

Medigap policies help pay costs that Original Medicare leaves to you. Whether you can buy one, and at what price, depends heavily on when you apply. The key rules are the Medigap open enrollment period and guaranteed issue rights.

Medigap open enrollment

Your Medigap open enrollment period is a one-time, six-month window that starts the first month you're 65 or older and enrolled in Part B. During this period, Medigap insurers generally:

• must sell you any policy they offer in your state;
• can't charge more because of health problems;
• can't deny coverage based on health.

Insurers may impose a waiting period for pre-existing conditions in some circumstances, which can be shortened or eliminated if you had prior creditable coverage.

This window doesn't repeat. If you delay Part B because of employer coverage, the window starts later, when Part B begins. See Medicare and employer coverage.

After the window: medical underwriting

Outside open enrollment, in most states insurers can ask health questions and may:

• charge more based on health;
• decline to sell you a policy;
• apply waiting periods for pre-existing conditions.

This is why switching from Medicare Advantage to Original Medicare later can be difficult if you want Medigap. See Medigap vs. Medicare Advantage.

Guaranteed issue rights

Federal law gives you the right to buy certain Medigap policies without underwriting in specific situations, typically within a limited time after the event. Examples include:

• your Medicare Advantage plan leaves Medicare or stops serving your area, or you move out of its service area;
• your employer or union coverage that pays after Medicare ends;
• your Medigap insurer goes bankrupt or ends your policy through no fault of your own;
• trial rights: you joined a Medicare Advantage plan when first eligible at 65 and want to leave within the first year, or you dropped Medigap to try Medicare Advantage for the first time and want to switch back within the first year.

Which plans you can buy under each right is limited, and strict timeframes apply. Keep letters and notices that show when coverage ended.

State rules can be broader

Some states give additional protections, such as yearly windows to switch Medigap plans without underwriting, or continuous guaranteed issue. A few states require insurers to offer Medigap to people under 65 who have Medicare due to disability. Rules vary widely, so check your state insurance department or SHIP program.

Practical points

• Decide carefully at 65. The open enrollment window is the easiest time to buy Medigap.
• Medigap plans are standardized by letter in most states, so comparing premiums across insurers for the same letter is straightforward.
• Ask how premiums are rated: community, issue-age, or attained-age, since that affects future increases.
• Don't cancel existing coverage until a new policy is approved.

The takeaway

The six-month Medigap open enrollment period is the one time most people can buy any Medigap policy without health questions. Outside it, specific guaranteed issue rights and state rules are the main protections. Knowing these rules before choosing between Medigap and Medicare Advantage can prevent a hard-to-reverse decision.

Sources

• Medicare.gov: Joining a plan
• Medicare.gov: Medicare & You handbook