When you can sign up — and what happens if you miss it

Medicare's deadlines are the part that actually costs people money. Not choosing the wrong plan — choosing late.

Your first window: seven months around your birthday

This is the Initial Enrollment Period. It runs for seven months:

• the three months before the month you turn 65,
• the month you turn 65,
• and the three months after.

Signing up in the three months before your birthday month is the tidiest option, because your coverage can start the first day of your birthday month with no gap.

Work out your own dates

Choose the month and year you were born and your dates will appear here. Nothing is sent anywhere — this works out the dates in your browser.

Nothing here is sent anywhere — it works the dates out in your browser. There's a page of its own for this if you'd rather send it to somebody.

If you're still working at 65

This is the most common source of confusion, and the answer genuinely depends on your employer.

If you have health coverage through a job — yours or your spouse's — you may be able to delay Part B without any penalty, and pick it up later through a Special Enrollment Period when that job coverage ends.

The penalties, plainly

Part B. If you don't sign up when you're first eligible and you don't have qualifying coverage from a job, your monthly premium goes up by 10% for each full 12-month period you could have had it and didn't. That increase doesn't expire — you pay it for as long as you have Part B.

Part D. A similar idea for drug coverage. If you go without creditable prescription coverage for 63 days or more after your window closes, a permanent amount gets added to your Part D premium, calculated from how many months you went without.

This is why people who take no medications at all often still enroll in a drug plan. It isn't for this year. It's insurance against the penalty and against a diagnosis you can't schedule.

Work out what it would cost

Say roughly how many months you went without it, and the estimate will appear here.

The window nobody tells you about

Here's the one that matters most, and the reason this page exists.

When you're 65 and enrolled in Part B, a six-month Medigap Open Enrollment Period starts. During it, you can buy any Medicare Supplement plan sold in your state, and the company cannot turn you down or charge you more because of your health.

After those six months, that protection is gone in most states. Apply later and the insurance company can ask about your health history and decline you. A condition you develop at 67 can close a door that was wide open at 65.

The yearly windows, after you're in

• October 15 to December 7 — the Annual Enrollment Period. You can change your Medicare Advantage or Part D plan for the year ahead. Plans change their costs and drug lists every year, so it's worth actually looking, even when nothing about your health has changed.
• January 1 to March 31 — if you're in a Medicare Advantage plan, you get one chance to switch to a different one or go back to Original Medicare.

What to do next

Work out two dates: the month you turn 65, and the month your employer coverage would end if you're still working. Almost every Medicare decision hangs off one of those.

If you're within a year of either, that's the right time for a conversation — not because something needs buying, but because the windows are easier to plan for than to recover from.