When to sign up for Medicare — and what it costs if you miss the window.
Medicare timing is unforgiving. Enroll in the right window and you pay the standard 2026 Part B premium of $185/month. Enroll late without qualifying coverage and that premium goes up 10% for every 12 months you waited — permanently. Here's exactly when to sign up, and the Special Enrollment Periods that can protect you.
Key takeaways
- Your Initial Enrollment Period (IEP) is 7 months long: 3 months before, your birthday month, and 3 months after
- If you have active employer coverage from a 20+ employee plan, you can usually delay Part B without penalty
- COBRA does NOT count as creditable coverage for delaying Part B — this catches many people off guard
- Part B late penalty: 10% / year, lifetime. Part D late penalty: 1% / month, lifetime
- Missed your IEP and don't qualify for an SEP? The General Enrollment Period runs Jan 1 – Mar 31
On this page
Your Initial Enrollment Period (IEP) — 7 months around your 65th birthday
This is the easiest, cheapest, and lowest-friction way to enroll in Medicare. Miss it without a qualifying reason and you're looking at penalties and a delayed coverage start date.
Your IEP runs for 7 months total:
- The 3 months before your 65th birthday month
- Your birthday month itself
- The 3 months after your birthday month
Example: If you turn 65 on September 12, 2026, your IEP runs June 1, 2026 through December 31, 2026. The month you enroll in changes when your coverage actually starts, though:
- Enroll in one of the 3 months before your birthday month → coverage starts the first of your birthday month
- Enroll during your birthday month or later → coverage is delayed up to a month past sign-up
Translation: if you want coverage to start the day you turn 65, sign up in one of those first three months. Waiting until your actual birthday can create a gap.
Automatic enrollment: If you're already receiving Social Security or Railroad Retirement benefits when you turn 65, you're usually enrolled in Part A and Part B automatically. Watch your mail around your 64th birthday for the Medicare & You handbook and your red, white, and blue Medicare card.
Special Enrollment Periods (SEPs) that let you delay without penalty
working past 65 with employer coverage
If you or your spouse are actively working and covered by a group health plan from an employer with 20+ employees, you can usually delay Part B without penalty.
When the job or coverage ends, you get an 8-month Special Enrollment Period to sign up for Part B. Most advisors recommend enrolling in the first 2 months to avoid any gap.
Important: COBRA and retiree coverage do not count as creditable for this SEP. If you go onto COBRA at retirement, the clock is still ticking.
Life events that trigger an SEP
A number of changes in your life open a new enrollment window for Medicare Advantage and Part D plans:
- Moving to a new service area or ZIP
- Losing creditable drug or employer coverage
- Moving into or out of a skilled nursing facility
- Qualifying for Medicaid or Extra Help
- A 5-star plan becoming available in your area
SEP rules vary by event. When something changes, call — we'll tell you which window applies to you.
Confused about which window applies to you?
Tell us your birth month and your situation — we'll map out your exact enrollment dates, flag any penalty risk, and walk you through the plan options in your ZIP. Free, no obligation.
Late enrollment penalties, in real dollars
Medicare's late penalties aren't a one-time slap on the wrist. They attach to your premium and stay there as long as you have Medicare.
Part B late enrollment penalty
For every full 12-month period you could have had Part B but went without it, your premium goes up 10%. And that premium is based on the current standard premium, not the one from the year you turned 65.
Example: You were eligible at 65 but didn't enroll for 3 years. Your Part B premium increases by 30%. On the 2026 standard premium of $185/month, that's an extra $55.50/month — $666/year — every year for the rest of your life.
Part D late enrollment penalty
If you go 63 or more consecutive days without creditable prescription drug coverage after your IEP, Medicare adds a penalty of 1% of the national base beneficiary premium × the number of months you went without coverage.
That base premium is recalculated each year, so the penalty quietly grows with time. People who thought they could "wait and see" because they weren't on many medications often regret it in their 70s when they need a plan.
General Enrollment Period — the fallback
If you didn't enroll during your IEP and don't qualify for an SEP, your next shot at Part A and Part B is the General Enrollment Period, which runs January 1 through March 31 every year. Coverage now starts the month after you enroll, rather than being delayed until July as it used to be.
You can still pick up a Medicare Advantage or Part D plan through a corresponding enrollment window once your Part A and B are active. Late enrollment penalties typically still apply.
Frequently asked
I'm still working and my employer has fewer than 20 employees. What should I do?
Does COBRA count as creditable coverage?
Can I sign up for Medicare online?
Is there a penalty for delaying Part A?
How do I know if my current drug coverage is "creditable"?
Not sure which window you're in?
Talk through your options with a licensed SilverEdge advisor. We'll map out your exact enrollment dates, flag any penalty risk, and show you what coverage is available in your ZIP.