I'm healthy at 65. Can I wait and buy Medigap later? The six-month window that comes once

You feel fine, and extra insurance feels like paying for nothing

You signed up for Original Medicare. You feel good. You see a doctor once a year, maybe twice.

A Medigap quote lands in the mail. It is one more monthly premium on top of Part B. You think, sensibly, that you will look at it later if something comes up.

Most people think the same thing. And most people assume "later" works the same as "now."

Now picture two years on. A diagnosis. You apply for a Medigap policy. This time the company asks about your health. It quotes a price you can't pay, or it says no.

That can happen because a one-time window closed while you weren't looking.

Why "you can always add it later" is wrong for Medigap

Plenty of coverage works on a yearly cycle. Drug plans do. Advantage plans do. Every fall, October 15 to December 7, you can switch.

So it is natural to think Medigap does too. It does not. The fall windows do not give you a federal right to buy Medigap.

Here is the rule in the official guide, written by Medicare and the National Association of Insurance Commissioners: "Your 6-month Medigap Open Enrollment Period starts the first month you have Medicare Part B and you're 65 or older. This is a one-time enrollment period; it doesn't repeat every year."

During those 6 months, a company must sell you any Medigap policy it offers in your state. It can't turn you down for your health. It can't charge you more for your health.

After the 6 months, those protections end for most people. The guide adds that the window "can't be changed or repeated." Once Part B starts after 65, the 6 months run whether you buy a policy or not.

Find your own six months, then decide

Here is the one idea worth taking from this page. Before you decide anything about Medigap, write down the month your window closes.

The window starts when two things are true: you have Part B, and you are 65 or older. For most people that is the month they turn 65. Count six months from there.

If you put off Part B because you have coverage from a current job, your window waits too. The guide says that when you sign up for Part B later, "your Medigap Open Enrollment Period will start when you're ready to take advantage of it." This case is easy to miss, so we flag it: the window did not start at 65.

Some details inside the window:

• Health problems you already have. A policy may make you wait up to 6 months before it covers a problem you had before it started. If you had at least 6 months of steady health coverage before, with a break of no more than 63 days, the wait may not apply.
• Plans C and F. If you became eligible for Medicare on or after January 1, 2020, you can't buy them. The other lettered plans are still sold.
• Plan letters. In most states plans are named A through D, F, G, and K through N. Every plan with the same letter has the same basic benefits, whatever company sells it.

The full Choosing a Medigap Policy guide has the details for each letter.

If you are healthy, look at prices while the window is open

Being healthy is a good time to compare, because inside the window your health can't change the price. A few facts help when you start.

• Each company sets its own price. Medicare's Medigap cost page says each insurance company decides how it will set the premium. Two policies with the same letter can cost quite different amounts.
• The benefits match, the price does not. Every plan with the same letter has the same basic benefits, whichever company sells it. The handbook says costs can vary "for exactly the same coverage, and may go up as you get older."
• Some companies give discounts. Medicare lists examples such as paying once a year, paying electronically, or having more than one policy with the company.
• You pay it on top of Part B. The Medigap premium goes to the private company. Your Part B premium still goes to Medicare.

You can look up the Medigap policies sold where you live on Medicare.gov. A SHIP counselor can also help you compare them for free.

The later chances that do exist

The window is not the only door. It is the widest one.

Federal law gives a few more chances to buy Medigap without health questions. In most of them you must apply within 63 days after your old coverage ends. They include an Advantage plan leaving your area, a job-based plan that pays after Medicare ending, and a Medigap company going bankrupt.

Two of them are trial rights, for people who try Medicare Advantage and change their mind. If you joined an Advantage plan when you first got Part A at 65, and you leave within the first year, you can buy any Medigap policy sold in your state. For both trial rights, you can apply as early as 60 days before your plan coverage ends and no later than 63 days after.

Some states add more. New York requires insurers to accept a Medicare enrollee's application "at any time throughout the year." California has a 60-day window after your birthday each year to switch to a policy with the same or fewer benefits. Oklahoma's insurance department describes a 60-day window that begins on your birthday. These birthday rules help people who already have Medigap and want to switch. They don't help a first-time buyer.

Keep the paperwork. The guide tells people to keep ending letters, claim denials and even the postmarked envelope as proof of dates.

The chapter that tracks this window

This is the problem The Year You Turn 65 was written for. Nancy Whitaker gives the window its own chapter, because it only runs once.

The Month Part B Starts: The Six Months Medigap Gives You Once has the rule in the guide's own words, what starts the clock, the waiting period, Plans C and F, every protected right with its dates, both trial rights and the three state rules the book checked on the states' own websites.

Before You Choose: Original Medicare or Medicare Advantage shows why going back to Original Medicare does not promise you a Medigap policy.

Still Working at 65 explains how putting off Part B moves your Medigap window with it.

The book is not affiliated with Medicare or Social Security, and it does not tell you whether to buy. Your State Health Insurance Assistance Program (SHIP) gives free counseling on Medigap plans, and your State Insurance Department can tell you about your state's extra windows. Social Security can confirm the date your own Part B starts.