Medicare Supplement

Medigap basics for Oceanside: what the letters cover

Medicare Supplement insurance — better known as Medigap — is one of the most misunderstood pieces of Medicare. For Oceanside residents weighing their options, knowing what Medigap does (and doesn't do) can make the difference between a smooth year and a stack of surprise bills.

Medigap policies are sold by private insurers, but the benefits inside each lettered plan are standardized by federal law. That means a Plan G from one company covers the same core benefits as a Plan G from another. The price and customer service can differ, but the coverage inside the plan letter does not.

What Medigap is actually designed to do

Original Medicare pays a big share of your hospital and doctor bills, but it leaves gaps — the Part A hospital deductible, the 20% coinsurance on most Part B services, and no cap on what you could owe in a bad year. Medigap steps in to help pay some or all of those leftover costs.

Depending on the letter you choose, a Medigap plan may cover:

• Part A hospital coinsurance and an extra 365 days of hospital coverage
• Part B coinsurance or copayments
• The first three pints of blood
• Hospice care coinsurance
• Skilled nursing facility coinsurance
• The Part A deductible
• Foreign travel emergency care (up to plan limits)

What Medigap does not cover: prescription drugs, long-term care, dental, vision, hearing aids, or private-duty nursing. Those need separate coverage.

How the standardized letters work

In most states, including California, Medigap plans come in 10 standardized letters: A, B, C, D, F, G, K, L, M, and N. Two things to know:

• Plans C and F are only available to people who became eligible for Medicare before January 1, 2020. If you turned 65 after that date, you generally can't buy them.
• Plans K and L have out-of-pocket limits, then pay 100% of covered services for the rest of the year. Plan N has small copays for some office and ER visits.

Plans G and N are the most commonly chosen among newer enrollees, but the "right" letter depends on how you use care, not on what's popular.

California adds one extra rule: the birthday rule

Oceanside is in San Diego County, and California has a consumer protection called the "birthday rule." Once you already have a Medigap policy, you get a window each year around your birthday to switch to another Medigap plan with equal or lesser benefits — without medical underwriting. That's a big deal, because outside of protected windows, insurers in most states can ask health questions and turn you down.

Your best shot at getting any Medigap plan you want, though, is your one-time six-month Medigap Open Enrollment Period, which starts the month you're 65 or older and enrolled in Part B. During that window, you have guaranteed issue rights.

Medigap vs. Medicare Advantage — you pick one lane

This trips up a lot of people: you cannot have both a Medigap plan and a Medicare Advantage plan at the same time. Medigap only works with Original Medicare.

• If you stay with Original Medicare, you can add a Medigap policy and a stand-alone Part D drug plan.
• If you choose Medicare Advantage, your coverage comes through that plan instead, and Medigap can't pay its cost-sharing.

San Diego County has a wide range of Medicare Advantage and Part D options each year, so many Oceanside residents compare both paths before deciding.

Don't forget Part D

Because Medigap doesn't cover prescriptions, most people with Original Medicare pair it with a stand-alone Part D plan. A few 2026 numbers worth knowing:

• The Part D out-of-pocket cap is $2,100.
• The maximum Part D deductible is $615.
• The old "donut hole" coverage gap was eliminated as of 2025 — Part D now has three phases.
• The Medicare Prescription Payment Plan lets you spread drug costs across the year in monthly installments if you choose.

Higher-income enrollees may also pay an IRMAA surcharge on Part B and Part D; for 2026, IRMAA starts above $109,000 in income for a single filer.

Key dates to keep in mind

• Medigap Open Enrollment: the six months starting when you're 65 and enrolled in Part B (one-time, personal to you).
• Medicare Annual Enrollment Period: October 15 – December 7 (for Part D and Medicare Advantage changes).
• Medicare Advantage Open Enrollment: January 1 – March 31.
• California birthday rule: a 60-day window tied to your birthday each year to switch Medigap plans without underwriting.