Medicare Advantage

San Diego Medicare: How Medigap Letter Plans Are Standardized

People in San Diego can choose from 85 Medicare Advantage plans for 2027, against 93 this year. 26 of this year’s plans are gone, 18 are new to San Diego County, and 48 that continue have changed their premium, deductible, plan type or name, 20 of them under a new name.

SAN DIEGO — If you're weighing Medicare choices in San Diego this fall, the calendar matters as much as the coverage. San Diego is in San Diego County, where 65 Medicare Advantage plans are on the shelf for 2027 from 15 carriers — a smaller menu than last year, but one that still needs sorting through before the enrollment window closes.

The rules around when you can enroll, switch or drop a plan are strict. Miss a window and you may be stuck with your current coverage for a full year, or face a late-enrollment penalty that follows you for life. Here's how the timing works this fall and what to do if a date slips by.

Your first window: the Initial Enrollment Period

When you first become eligible for Medicare — usually around your 65th birthday — you get a seven-month Initial Enrollment Period. It starts three months before the month you turn 65, includes your birthday month, and ends three months after.

Signing up in the three months before your birthday month means your coverage can start the month you turn 65. Wait until later in the window and coverage starts later. Skip it entirely without other qualifying coverage and you may pay a Part B late-enrollment penalty of 10% for every 12 months you delayed — every month, for as long as you have Part B.

The Annual Enrollment Period: October 15 – December 7

This is the big one. Between October 15 and December 7 each year, anyone on Medicare can:

• Switch from Original Medicare to a Medicare Advantage plan, or vice versa.
• Change from one Medicare Advantage plan to another.
• Join, drop, or switch a Part D prescription drug plan.

Any change you make during AEP takes effect January 1, 2027. With 65 Advantage plans available across San Diego County for 2027, plus continuing program-wide changes to Part D (more on that below), don't leave your review until the first week of December.

The second window: Medicare Advantage Open Enrollment

If you're in a Medicare Advantage plan on January 1 and something isn't working — the network, the drug list, the provider you thought was included — you get another shot. From January 1 through March 31, you can switch to a different Advantage plan or drop Advantage entirely and return to Original Medicare (and add a Part D plan if needed).

This window is only for people already enrolled in Medicare Advantage. You can only use it once, and you can't use it to jump from Original Medicare into an Advantage plan.

When the calendar bends: Special Enrollment Periods

Life doesn't always line up with October 15. A Special Enrollment Period may open outside the normal windows if you:

• Move out of your plan's service area (including a move into or out of San Diego County).
• Lose employer or union coverage.
• Qualify for Extra Help or Medicaid.
• Live in a nursing facility.

SEPs usually last about two months from the qualifying event. If you think one applies, call 1-800-MEDICARE before you assume you have to wait for fall.

Why the timing this fall matters more than usual

Part D is changing in ways that make it worth re-checking your drug coverage this AEP, even if you've been happy for years. The out-of-pocket cap on covered prescriptions is $2,100 in 2026 and $2,400 in 2027. The Part D maximum deductible is $615 in 2026 and $700 in 2027. The old "donut hole" coverage gap is gone, replaced by a simpler three-phase design that started in 2025. And the Medicare Prescription Payment Plan lets you spread your drug costs across the calendar year in monthly installments instead of paying big amounts at the pharmacy counter.

Higher-income enrollees should also note the IRMAA surcharge, which begins above $109,000 in income for a single filer in 2026 and adds to Part B and Part D premiums.

None of that changes the deadlines — but it does mean the plan that fit you in 2026 may not be the same plan in 2027. AEP is the time to check.

What to do if you miss a window

If you miss your Initial Enrollment Period, the General Enrollment Period (January 1 – March 31) lets you sign up for Part B, with coverage starting the month after you enroll. Late penalties may still apply.

If you miss AEP, you're generally locked into your current coverage until the next AEP — unless you qualify for a Special Enrollment Period or you're in an Advantage plan and can use the January–March window.

Where to get unbiased help

With 65 Medicare Advantage options in San Diego County for 2027, the smart move is to compare using neutral tools before you enroll:

• Medicare.gov Plan Finder — enter your ZIP code and your medications to see every plan in your area.
• 1-800-MEDICARE — 24/7, free.
• California SHIP (HICAP) — free one-on-one counseling for San Diego residents, with no ties to any insurance company.