What happens if you don't sign up for Medicare at 65?

If you don't sign up for Medicare at 65 and you don't have qualifying coverage from current work, you'll usually pay a Part B late penalty of 10% for every 12 months you waited, and a Part D penalty, both for as long as you have Medicare. You may also wait months for coverage to start. If you're covered by a large employer's plan through current work, you can usually wait without a penalty.

Medicare isn't mandatory, and many people delay parts of it for good reasons. The problem is delaying for the wrong reason, such as relying on COBRA, a retiree plan or an individual policy. Here's exactly what happens, what it costs in dollars, and how to fix it if you've already missed your window.

Is it mandatory to sign up for Medicare at 65?

No. But Medicare is built to reward signing up on time. Your Initial Enrollment Period lasts 7 months: 3 months before the month you turn 65, your birthday month, and 3 months after. Miss it without qualifying coverage and three things can happen: late penalties, a wait for coverage, and fewer choices for a Medicare Supplement.

If you already get Social Security benefits, you're enrolled in Parts A and B automatically. You can decline Part B by following the instructions with your card, but you can't turn down premium-free Part A while collecting Social Security retirement benefits.

Why people skip Medicare at 65

In our experience, most people who miss their window didn't decide to skip Medicare. They assumed it started automatically, believed COBRA or a spouse's retiree plan counted, liked their individual plan, or were simply overwhelmed by the mail and phone calls that arrive around 65. Every one of those can lead to a lifetime penalty, which is why it pays to check your situation 6 months before your birthday.

What happens, part by part

The Part B penalty in real dollars

The Part B penalty is a percentage of the standard premium, so it grows every year as the premium rises. Using the 2026 standard premium of $202.90:

Premium source: CMS 2026 fact sheet. Real lifetime costs are likely higher because the Part B premium rises most years.

The Part D penalty in real dollars

If you go 63 days or more without Part D or other creditable drug coverage after your window, the penalty is 1% of the national base premium ($41.33 in 2027) for each full month you went without, rounded to the nearest 10 cents.

It's smaller than the Part B penalty, but it lasts as long as you have Part D, and it grows with the base premium. More on Part D drug plans and 2027 costs.

The coverage gap nobody warns you about

Missing your window without a special enrollment period means waiting for the General Enrollment Period, January 1 to March 31. Your coverage starts the first day of the month after you sign up. Miss your window in May, and you might go without Part B until the following year. Any doctor visits, tests or surgery in between aren't covered by Medicare.

When you don't need to sign up at 65

• You're covered through current work (yours or your spouse's) at an employer with 20 or more employees. You can delay Part B and sign up within 8 months after the job or coverage ends.
• Your drug coverage is creditable. Your plan sends a yearly notice saying so. Keep it; you may need it to avoid a Part D penalty later.

Details, forms and HSA rules: signing up for Medicare while you're still working.

Coverage that won't protect you from penalties

• COBRA: your Part B window starts when your job ends, not when COBRA ends.
• Retiree health plans: usually expect you to have Parts A and B at 65.
• ACA Marketplace or individual plans: don't count, and your premium tax credits end once you're eligible for premium-free Part A.
• VA health care: doesn't count for Part B, though VA drug coverage counts for Part D.
• A small employer's plan (fewer than 20 employees): Medicare usually pays first, so skipping Part B can leave big bills unpaid.

Already missed your window? What to do now

1. Check for a special enrollment period. Besides the employer rule, Medicare has special enrollment periods for exceptional situations, such as a government-declared emergency or disaster that kept you from signing up, losing Medicaid, or getting wrong information from your employer or health plan.
2. If none applies, sign up in the General Enrollment Period (January 1 to March 31) through Social Security at ssa.gov or 1-800-772-1213.
3. Check for help with costs. If you qualify for a Medicare Savings Program, the state pays your Part B premium and you won't pay the Part B late penalty. People who get Extra Help don't pay the Part D penalty.
4. Appeal if the penalty is wrong. If you had creditable coverage, you can ask for a reconsideration and send your proof.
5. Plan your coverage. When Part B starts, your six-month Medigap window opens. Compare a Supplement against Advantage then.

A Florida note: hurricanes and disasters

South Florida residents know how a hurricane can upend everything for weeks. If a FEMA-declared emergency or major disaster in your area stopped you from signing up or changing plans on time, you may qualify for a special enrollment period. Keep records of when the emergency happened and when you tried to enroll, and call us or Social Security as soon as you can.

Two example situations

A 67-year-old in Coral Springs on an individual health plan. She skipped Part B at 65 because she liked her plan. The individual plan doesn't count, so she can sign up during the next General Enrollment Period and will pay a 20% Part B penalty for life: about $40.58 a month at 2026 prices. Signing up in January rather than waiting another year keeps it from rising to 30%.

A 66-year-old in Delray Beach who retired and kept COBRA. He left his job 5 months ago. He's still inside his 8-month Part B window, so if he signs up now with forms CMS-40B and CMS-L564, he avoids any penalty and gets his full Medigap window when Part B starts.

Avoid it in the first place

1. Mark your Initial Enrollment Period on the calendar: 3 months before your 65th birthday month.
2. If you're working, confirm in writing that your employer has 20 or more employees and that your coverage is from current work.
3. Keep every creditable coverage notice for your drug plan.
4. Talk to a licensed agent before you decide to wait. See the turning-65 Medicare timeline for Broward and Palm Beach.

We help South Florida families avoid these penalties at no cost, in English or Haitian Creole. Once you're enrolled, we'll help you choose between a Medicare Supplement and a Medicare Advantage plan; see Medigap vs Medicare Advantage.