Medicare vs. Covered California: What Happens When Your Parent Turns 65

Your parent has been on a Covered California plan for years — maybe since they lost employer coverage, or after a career change, or because it was simply the most affordable option. Now they're turning 65 and Medicare eligibility changes everything. The rules about what happens to Covered California when Medicare kicks in are not intuitive, and getting the transition wrong can mean losing premium tax credits, paying for duplicate coverage, or ending up uninsured during a gap.

Here's the complete picture for adult children helping a California parent move from a Marketplace plan to Medicare.

The Short Answer: You Cannot Have Both

The most important rule to understand upfront: Medicare-eligible individuals cannot receive premium tax credits (PTCs) through Covered California. The Affordable Care Act specifically prohibits individuals who are eligible for Medicare — not just enrolled, but eligible — from receiving subsidies on a Marketplace plan.

This means the moment your parent becomes eligible for Medicare (generally the first day of their birth month when they turn 65, or earlier if they qualify through disability or ESRD), they lose the right to premium tax credits. If they continue on Covered California past that eligibility date while receiving subsidies they're no longer entitled to, they may owe those credits back to the IRS when they file taxes.

Some parents don't realize this and stay on Covered California for months after becoming Medicare-eligible. This is a tax problem, not just a health insurance problem.

Why Families End Up in This Situation

Covered California plans work well for people in their 50s and early 60s who don't have employer coverage. The premium tax credits can make a $1,500/month individual plan cost $200 or less depending on income. Many families rely on these plans for years before Medicare eligibility arrives.

The problem is that Covered California enrollment is largely automated — you re-enroll each fall, premiums adjust, and the plan renews. Medicare eligibility doesn't automatically cancel the Covered California plan. Your parent has to actively transition, and there's a specific sequence of steps to do it without creating gaps or IRS complications.

What Happens to the Covered California Plan at Age 65

Automatic termination of subsidies: When your parent becomes eligible for Medicare, premium tax credits end. If they remain on the Covered California plan, they can technically keep it — but they pay the full unsubsidized premium, which in California often runs $1,200–$2,000+ per month for a 65-year-old. Very few families choose to pay this when Medicare is available.

No disruption to ongoing care (temporarily): The Covered California plan itself does not vanish the day they turn 65. Coverage continues until your parent actively cancels it or lets it lapse. But they're now paying full premium without tax credits, and they may also be paying Medicare premiums. Carrying both is extremely expensive and generally makes no financial sense.

Special Enrollment Period for Covered California: Your parent can cancel their Covered California plan at any time after becoming Medicare-eligible. Losing subsidies due to Medicare eligibility qualifies as a Special Enrollment Period. This is worth knowing because it means they don't have to wait until the Marketplace open enrollment period (November 1–January 31) to leave.

The Correct Sequence: How to Transition

Step 1: Enroll in Medicare during the Initial Enrollment Period (IEP)

The IEP is the 7-month window surrounding your parent's 65th birthday:

• Starts 3 months before the birth month
• Includes the birth month
• Ends 3 months after the birth month

Enroll in Medicare Part A and Part B through SSA.gov or at a Social Security office. Part A takes effect on the first day of the birth month if enrolled during the 3 months prior. Part B typically takes effect the same way.

Do not delay enrollment to finish out a Covered California plan year. The Medicare late-enrollment penalty for Part B is permanent (10% per 12-month delay, added to premiums for life). No Covered California benefit is worth triggering that penalty.

Step 2: Choose Medigap or Medicare Advantage during the guaranteed-issue window

When Part B becomes effective, a 6-month Medigap Open Enrollment Period opens. During this window, your parent can buy any Medigap policy in California with guaranteed-issue rights — no health questions, no denial based on pre-existing conditions.

This window does not repeat. Once it closes, California insurers can use medical underwriting to deny Medigap coverage or charge higher premiums based on health status. (California does have an annual birthday rule that provides some ongoing flexibility, which we cover below — but the initial 6-month window offers the broadest protection.)

During the same period, your parent can also enroll in a Medicare Advantage plan instead of Medigap. They can use the Medicare Plan Finder at Medicare.gov to compare options available in their California county.

Step 3: Select a Part D drug plan

If your parent chooses Original Medicare plus Medigap, they need a stand-alone Part D prescription drug plan. If they choose Medicare Advantage, most MA plans include drug coverage. Compare Part D plans using their actual medication list — formulary differences can mean hundreds of dollars per year.

Step 4: Cancel the Covered California plan

Once Medicare coverage is confirmed and active, contact Covered California to cancel the plan. Log in to the Covered California account, report the change in circumstances (Medicare eligibility), and select an end date. Coordinate the dates so there is no gap: Medicare effective date and Covered California termination date should align.

Don't cancel the Covered California plan before Medicare is confirmed. If there's any administrative delay in Medicare Part B processing, your parent could end up with neither coverage for a period. Keep Covered California active until you have the Medicare card in hand and have confirmed the effective date.

Step 5: Reconcile the tax credit on the next tax return

If your parent received premium tax credits in the months before their Medicare effective date, those subsidies are legitimate and don't need to be repaid — they were eligible for the credits during those months. But if they continued receiving credits after their Medicare eligibility date, those must be repaid when filing. Use Form 8962 to calculate the reconciliation. If the amount owed is significant, consult a tax professional.

California-Specific Rules That Help

California has two consumer protection rules that make the Medigap transition more flexible than in most other states:

The California Birthday Rule

California law allows Medigap policyholders to switch to a different Medigap plan of equal or lesser benefit during a 60-day window each year around their birthday — without medical underwriting. This means your parent can:

1. Enroll in any Medigap plan during their initial 6-month open enrollment window (guaranteed issue)
2. Then shop their rate every year around their birthday to find a lower premium from a different insurer

This is a significant protection that most states don't offer. It prevents California residents from being trapped in an expensive Medigap policy simply because they enrolled with the wrong insurer initially. Your parent can start with one insurer and switch annually based on price.

Guaranteed Issue for Medicare Advantage Exits

California residents who leave a Medicare Advantage plan to return to Original Medicare do not automatically get guaranteed-issue Medigap rights — this is federal law and California follows it. However, the birthday rule applies to Medigap plan-switching (not initial enrollment), which provides ongoing flexibility once your parent is in the Medigap ecosystem.

Common Mistakes in the Covered California to Medicare Transition

Waiting until Covered California open enrollment to make the switch. Your parent doesn't need to wait until November. Medicare eligibility triggers a Special Enrollment Period for Marketplace plans. Delaying past the Medicare IEP to "finish out the Covered California year" risks a Part B late enrollment penalty.

Assuming Covered California will automatically end. It won't. Your parent must actively cancel it. Continuing to pay full premiums for a Covered California plan while also paying Medicare premiums is expensive and unnecessary.

Not selecting Medigap during the guaranteed-issue window. The 6-month window after Part B enrollment is the best time your parent will ever have to buy comprehensive supplemental coverage. Waiting means facing medical underwriting. In California, the birthday rule provides some future flexibility, but it only lets you switch among Medigap plans — not add one for the first time after the window closes.

Choosing Medicare Advantage because it's free without comparing long-term costs. A $0-premium Medicare Advantage plan looks appealing after years of paying Covered California premiums. But the $0 premium comes with a network, prior authorization requirements, and an out-of-pocket maximum up to $9,350. If your parent's health is declining or unpredictable, Original Medicare plus Medigap often costs less in total over a serious illness year.

Not checking income for IRMAA. If your parent's income was above $106,000 (single filer) in the past two years, they will pay an Income-Related Monthly Adjustment Amount (IRMAA) surcharge on top of the standard Part B and Part D premiums. This surcharge is based on tax returns from two years prior. If income has dropped significantly due to retirement, file Form SSA-44 with Social Security to request a reduction based on current-year income.

How Covered California Differs from Medicare: A Quick Reference

Getting the Transition Right

The Covered California to Medicare transition involves more moving parts than most families expect: IEP timing, Medigap open enrollment, Part D selection, tax credit reconciliation, and coordinating cancellation dates. Each piece has consequences if handled out of order.

The Medicare Enrollment Guide was designed specifically for adult children managing this complexity on behalf of a parent — with enrollment period timelines, plan comparison frameworks, and the step-by-step decision logic to avoid the most costly mistakes. If your parent is within 6 months of turning 65 and still on a Covered California plan, now is exactly the right time to start.