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Parts A, B, C and D
The dates matter more than the plans
Almost everything written about Medicare is about choosing a plan. The thing that actually costs people money is missing a window — and one of those penalties is charged every month for the rest of your life.
Jan 1 – Mar 31General EnrolmentIf you missed your first window
Jan 1 – Mar 31Advantage switchOnly if you are already in one
Your 65thInitial Enrolment3 months before, to 3 months after
Oct 15 – Dec 7Open EnrolmentChange plans for the new year
The four parts
A, B, C and D — what each one is
Medicare is not one thing you sign up for. It is four parts, and you do not take all of them from the same place.
Part A — Hospital
Inpatient hospital stays, skilled nursing after a hospital stay, hospice, and some home health care.
Free for most peopleNo premium if you or a spouse worked about 10 years in Medicare-covered work.
Part B — Medical
Doctor visits, outpatient care, lab tests, scans, equipment and preventive care.
$202.90 a monthThe standard 2026 premium. Higher earners pay more. This is the part with the permanent late penalty.
Part C — Medicare Advantage
A private plan that delivers Parts A and B, usually bundles drug cover, and may add dental, vision or hearing.
Part B premium, plus any plan premiumYou still pay for Part B. Advantage plans cap what you spend in a year; Original Medicare does not.
Part D — Prescription drugs
Outpatient prescription medicines, through a private plan you choose.
Varies by planHas its own late penalty, on a much shorter clock than Part B — 63 days, not 8 months.
Original Medicare means Part A and Part B, usually with a Part D plan alongside. Medicare Advantage is the alternative route. You are choosing between those two shapes, not collecting all four.
Enrolment windows
Four windows, and only one is about your birthday
These are the dates. Everything else on this page matters less than these.
Your 65th birthday
Initial Enrolment
Seven months
Three months before your birthday month, that month, and three months after. Sign up early and cover starts on the 1st of your birthday month.
Born on the 1st? The whole window shifts a month earlier.
1 Jan – 31 Mar
General Enrolment
Yearly
For anyone who missed their first window and has no special one. Cover starts the 1st of the month after you sign up.
Changed in 2023. Most pages still say cover starts 1 July — that is out of date.
15 Oct – 7 Dec
Open Enrolment
Yearly
The one most people know. Switch between Original and Advantage, change plans, or join or drop drug cover. Changes start 1 January.
Does not let you join Part B for the first time.
1 Jan – 31 Mar
Advantage Open Enrolment
Yearly
Only if you are already in an Advantage plan. One change: switch plans, or return to Original Medicare and add drug cover.
While you are working
Special Enrolment
Job, plus 8 months
Still covered by an employer's group plan? You can usually delay Part B without penalty. The clock starts when the job or the cover ends.
Drug cover has its own, much shorter clock — 63 days.
The penalty trap
“I'm still working, so I'll wait”
Sometimes that is exactly right. Sometimes it costs you every month for the rest of your life. The difference is not obvious, and it is not about how you feel about it — it is about who your employer is and what your plan says.
Usually safe to delay
- You or your spouse are actively working and covered by that employer's group plan
- The employer has 20 or more employees, so their plan pays first and Medicare second
- Your drug cover has been certified in writing as “creditable” — keep that letter
Not safe, even though it feels like it should be
- The employer has fewer than 20 employees — Medicare becomes the main payer at 65 whether you enrol or not
- COBRA — it is not current-employment coverage, and the clock started when the job ended
- Retiree coverage — same problem as COBRA
- A Marketplace plan — it does not count, and the tax credit usually stops too
- VA coverage on its own — it does not protect you from the Part B penalty
What the Part B penalty actually is
An extra 10% on your premium for every full year you could have had Part B and did not. It is permanent — it is added for as long as you have Part B, and it rises each year as the standard premium rises. Part D has its own penalty, worked out from the months you went without drug cover.
What it costs
The 2026 numbers
These are set nationally and change every January. What you pay on top depends on the plans you choose.
| What | 2026 amount | How often |
|---|---|---|
| Part B premium (standard) | $202.90 | Every month |
| Part B deductible | $283 | Once a year |
| Part A premium, most people | $0 | — |
| Part A hospital deductible | $1,736 | Per benefit period |
| Hospital days 61–90 | $434 | Per day |
A benefit period is not a calendar year. A new one starts after 60 days out of hospital, so the hospital deductible can be charged more than once in a year.
The gap nobody mentions
Original Medicare has no annual limit on what you can spend out of pocket. Medicare Advantage plans must have one. That single difference is the real decision behind most of the plan marketing you will see.
CMS 2026 figures · KFF
Your dates
Which of these is you?
Pick the one that fits and we will send the windows that apply to you — not all of them. Everything on this page stays free and open either way.
Which of these is you?
Help with the cost
Two programmes worth asking about
Medicare Savings Programs
State-run programmes that can pay your Part B premium, and sometimes deductibles and coinsurance too. Income and asset limits apply and several states set theirs higher than the federal floor — so being turned down in one state does not tell you anything about another.
Apply through your state Medicaid office
Extra Help (Low Income Subsidy)
Cuts the cost of Part D drug coverage — premiums, deductible and what you pay at the pharmacy. Being enrolled in a Medicare Savings Program usually qualifies you automatically.
Apply through Social Security
Free official help
Where to go, and what each one is for
All free. None of them sells you anything, and you never need to pay someone to enrol.
Questions
Straight answers
The questions people ring the helpline about, answered without a sales pitch.
If you already receive Social Security before 65, you are usually enrolled in Parts A and B automatically and the card arrives in the post. If not, nothing happens on its own — you sign up yourself. Assuming it is automatic is a common way to miss the first window.
Often, but not always. Delaying is generally safe if you or your spouse are actively working under an employer plan with 20 or more employees. It is not safe with a small employer, COBRA, retiree coverage, a Marketplace plan or VA coverage alone. Ask your benefits office in writing whether their plan pays before or after Medicare.
An extra 10% on your monthly Part B premium for every full 12-month period you could have had Part B and did not. It is permanent — you pay it for as long as you have Part B — and because it is a percentage of the standard premium, the amount goes up each year as that premium rises.
Sign up in the three months before your birthday month and coverage starts on the first of that month. Sign up during or after it and coverage starts the first of the following month. The General Enrolment Period works the same way — that changed in 2023, and much published guidance still shows the old 1 July date.
A private policy covering some of what Original Medicare leaves you to pay. Its open enrolment runs six months from the first month you are both 65 and enrolled in Part B. Inside that window an insurer must accept you regardless of health; outside it, most states let them decline you or charge more. It runs once.
You can switch during Open Enrolment, or in the first three months of the year if already in an Advantage plan. What is not guaranteed is a Medigap policy alongside it — outside your one-time window most states allow underwriting. New York, Connecticut, Massachusetts and Maine are more generous.
Yes, and it is under-claimed. Medicare Savings Programs, run by your state, can pay your Part B premium and sometimes more. Extra Help, run by Social Security, reduces what you pay for prescription drugs. Both have income and asset limits, several states set theirs above the federal minimum, and both are free to apply for.
No. We are not Medicare, not a government agency, and not an insurance agent or broker. We sell nothing, we receive no commission, we take no applications and we cannot enrol anyone. Everything here is general information. Medicare will also never ring you out of the blue to sell you a plan — if someone does, that is a warning sign.
Every state has a State Health Insurance Assistance Program — SHIP — offering free one-to-one counselling from people who are not selling anything. You can also ring 1-800-MEDICARE at any hour, use the official Plan Finder at medicare.gov, or contact Social Security to enrol. The Medicare Rights Center runs a free national helpline as well.
Next step
Put the dates in your calendar, not in your memory
The windows are the whole game. Get yours by email, or go straight to Medicare.gov — we would rather you were enrolled on time than reading us.
Which of these is you?