Part A — hospital
Inpatient hospital, skilled nursing after a hospital stay, hospice. Usually no premium if you or a spouse paid Medicare taxes for 10 years.
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Reviewed for accuracy by Lauri Middleton, RN, MSN, licensed Medicare agentReviewed for clarity by Karen OrillaMeet our reviewers →
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California Medicare Guidance
Medicare at a glance
One page: the four parts, the two paths, the windows, the penalties, and the free help numbers. Dated, so you know when it was current.
California Medicare Guidance · Generated 2026-11-02 · Source version california-guidance-2026-09-05-v3 · Educational guidance, not an eligibility decision · Not affiliated with the U.S. government
Part B — medical
Doctor visits, outpatient care, tests, preventive services, equipment. Has a monthly premium; higher earners pay more.
Part C — Medicare Advantage
A private plan that provides Part A and B benefits, usually with a network, an out-of-pocket maximum, and often drug coverage and extras.
Part D — prescriptions
Prescription drug coverage from a private plan — either a stand-alone plan with Original Medicare, or built into a Medicare Advantage plan.
Medigap — fills Original Medicare’s gaps
A Medigap (Medicare Supplement) policy is private insurance that pays some of what Original Medicare does not, such as coinsurance and deductibles. Plans are standardized by letter. Your best guaranteed chance to buy one is the six months starting when you are 65 or older and enrolled in Part B; after that, an insurer can often ask health questions and charge more or refuse.
The windows
- Your first enrollment window lasts seven months — The Initial Enrollment Period starts three months before the month you turn 65, includes your birthday month, and ends three months after it. Signing up in the first three months usually means coverage starts the month you turn 65.
- After job coverage ends you have 8 months for Part B — If you delayed Part B because you or your spouse had coverage from current work, you get a Special Enrollment Period: 8 months starting the month after the job or the coverage ends, whichever comes first. Signing up in that time avoids the Part B penalty.
- If you missed your window, there is a yearly catch-up period — The General Enrollment Period runs January 1 through March 31 every year. If you sign up then, coverage starts the month after you sign up. A late-enrollment penalty may still apply.
- October 15 to December 7: the yearly window to change plans — Every year during Open Enrollment you can switch between Original Medicare and Medicare Advantage, change Medicare Advantage plans, or join, drop or change a drug plan. Changes take effect January 1.
- January to March: one more chance if you are in Medicare Advantage — From January 1 to March 31, people enrolled in a Medicare Advantage plan can make one change: switch to a different Medicare Advantage plan, or go back to Original Medicare (and join a drug plan).
The penalties
- Signing up late for Part B usually costs extra for life — If you sign up for Part B after your first window ends and did not have coverage from current work in between, Medicare generally adds 10% to your Part B premium for every full 12 months you could have had Part B but did not — and the extra amount usually lasts as long as you have Part B.
- Drug coverage has its own, separate penalty — If you go 63 days or more without Medicare drug coverage or other creditable drug coverage after your first window, Medicare generally adds a monthly amount to your Part D premium for as long as you have drug coverage. It is based on how many months you went without.
Free help
California HICAP offers free, confidential Medicare counseling. Ask the local program about language and appointment availability. 1-800-434-0222
Call 1-800-MEDICARE and ask for an interpreter. TTY: 1-877-486-2048.
Get help
Free Medicare counseling
California HICAP offers free, confidential Medicare counseling. Ask the local program about language and appointment availability.
California HICAP1-800-MEDICARE
Call 1-800-MEDICARE and ask for an interpreter. TTY: 1-877-486-2048.
Call Medicare · 1-800-633-4227Official information in other languages ↗External resource. Some pages are in English; ask for language assistance if needed.