Blog / Medigap

How do I enroll in a Medicare Supplement?

The application, the timing that decides whether you can be declined, and the order that keeps you from a coverage gap.

Updated August 17, 2026 · 3 min read

Buying a supplement is an insurance application rather than a Medicare enrollment. You apply directly with the carrier, and Medicare is not involved beyond your Part A and Part B enrollment.

What you need first

• Enrollment in both Part A and Part B
• Your Medicare number and your Part A and Part B effective dates, from your red, white and blue card
• Ideally, to be inside your six month Medigap open enrollment window

That last item is not a requirement but it changes everything about the application. See your open enrollment window.

The timing that decides the outcome

Inside your six month window, which starts when Part B begins at or after 65, no Texas carrier can decline you or charge more for your health history. The application is essentially a formality.

Outside it, unless you have a guaranteed issue right, the carrier can underwrite. Health questions, possible higher rates, possible decline.

Choosing before you apply

1. Pick your plan letter. Plan G for most people newly eligible, Plan N for a lower premium with small copays, high deductible Plan G for a much lower premium. See choosing a letter.
2. Get quotes for that letter from several carriers.
3. Ask each for the pricing method and the rate increase history.
4. Ask about household and payment discounts.
5. Choose on price, since coverage is identical by law. See comparing rates.

The application

• Personal and Medicare information
• Health questions, if you are outside a protected window
• Your requested effective date
• Payment setup, often with a discount for electronic funds transfer

Answer health questions accurately. A misstatement can allow the carrier to rescind the policy later, which is far worse than a decline today.

The order that avoids a gap

1. Apply and wait for written approval with a confirmed effective date.
2. Enroll in a standalone Part D plan for the same effective date, since supplements include no drug coverage. See why you need Part D.
3. If you are leaving a Medicare Advantage plan, only disenroll after the supplement is approved. See switching from Advantage.
4. If you are replacing an existing supplement, set the old one to end the day before the new one starts.
5. Confirm everything in writing before any coverage terminates.

After you are approved

You get a policy and a card. Carry it with your Medicare card. Providers bill Medicare, which forwards the balance to the carrier automatically, so you should not need to file claims.

You also get a 30 day free look period in which you can cancel for a refund if you change your mind.

There is no annual renewal decision. Medigap policies are guaranteed renewable and continue as long as you pay the premium. Reviewing your rate against the market every couple of years is still worth doing, while you are healthy enough to move if you want to.