Medicare Open Enrollment October 15 to December 7, 2026: Medicare Advantage vs Medigap Plan G Costs by Deductible, Location, and Nursing Home Risk

Today is September 23. Medicare's Annual Enrollment Period opens October 15 and closes December 7, which leaves about three weeks to gather what you need. Every plan change you make lands on January 1, 2027.

If you already have Medicare, you probably have some version of these questions. Is my Medicare Advantage plan still worth keeping? Will my drug plan's formulary change? Can I still see my surgeon? What happens if I need a nursing facility after a hospital stay?

The honest answer to most of them is "it depends on your plan, your deductible status, your ZIP code, and which facility you use." This post gives you the numbers and the sequence of decisions, so you can plug in your own.

The 4 enrollment windows and what each one lets you do

Before comparing costs, confirm which window you are in. It decides what you can change and whether a Medigap insurer can turn you down.

Window	Dates	What you can do	Underwriting risk
Initial Enrollment Period (IEP)	7 months around your 65th birthday: 3 months before, the month of, 3 months after	Enroll in Parts A, B, D, or Medicare Advantage	None
Medigap Open Enrollment	6 months starting when you are 65+ and enrolled in Part B	Buy any Medigap plan sold in your state	None. This is a one-time window in most states.
Annual Enrollment (AEP)	Oct 15 to Dec 7	Switch MA plans, switch Part D plans, move from MA to Original Medicare	Yes, if you go back to Original Medicare and want Medigap (most states)
MA Open Enrollment (MA OEP)	Jan 1 to Mar 31	If you're in MA, switch MA plans or drop to Original Medicare (one change)	Same Medigap underwriting risk

A Special Enrollment Period (SEP) applies in narrower circumstances: you move out of your plan's service area, you lose employer coverage, or your plan leaves Medicare.

The irreversible decision: if you are past your Medigap open enrollment window and you leave Medicare Advantage for Original Medicare, most states let a Medigap insurer look at your health history and decline you or charge more. A handful of states (New York, Connecticut, Massachusetts, Maine, and a few others) have more forgiving rules. Check your state before you drop MA.

For the full window-by-window breakdown, see our guide to switching from Medicare Advantage without underwriting.

Why the plan you had last year may not be the plan to keep

Several stories in this week's news point to the same pressure: costs are rising and people are noticing.

A KFF-AP poll of rural voters found the cost of living and the cost of health care are the top issues they want to hear about from midterm candidates.
KFF Health News reported on health care workers, people who know the risks better than most, who saw premiums rise by hundreds of dollars a month and chose to go uninsured. Some cannot afford to.
At a Tuesday event, CMS Administrator Dr. Mehmet Oz described Medicare Advantage as a garden "vulnerable to weeds and overgrowth," per Healthcare Dive. That is a signal that federal scrutiny of MA payments and practices continues. It does not tell you what your specific plan will do in 2027. For that background, see what the CMS 2027 payment rate increase means for your premiums.
Medicare Rights Center reported that thousands of immigrants are scheduled to lose Medicare coverage in the new year under H.R. 1, and it commented on the proposed CMS rule that implements those changes. If that could affect you or a family member, contact Social Security or a SHIP counselor now, not in January. Our post on H.R. 1 eligibility changes and Part D costs covers the drug-cost side.
KFF Health News also reported that nursing home beds are becoming scarcer as the oldest baby boomers turn 80. That matters for the skilled nursing scenario below.

The 2026 numbers you need

These are the CMS figures for 2026. Confirm the 2027 figures when CMS publishes them this fall.

Part B premium: $202.90/month ($2,434.80/year)
Part B deductible: $283
Part A hospital deductible: $1,736 per benefit period
Skilled nursing coinsurance: $0 for days 1-20, $217/day for days 21-100, and everything after day 100 is yours
Part D out-of-pocket cap: $2,100 for the year
Medicare Advantage in-network out-of-pocket maximum (MOOP): up to $9,250 (plans can set lower)
IRMAA: based on your income from two years back. Based on Toravine's analysis of the CMS IRMAA fact sheet dataset (174 rows), the first surcharge tier begins around $109,000 for a single filer and $218,000 for a married couple filing jointly. It raises Part B to roughly $284 per month before you buy anything else.

Worked example: three scenarios for the same 67-year-old

Assume a single 67-year-old with income below the IRMAA threshold and a Part D drug plan with a $40/month premium. Assume drugs cost $2,100 under either approach (the Part D cap), so we can isolate everything else.

Plan A: Original Medicare + Medigap Plan G + Part D

Plan G premium: $170/month. Our analysis of the medigap_rates dataset (3,570 rows) shows Plan G premiums varying widely by state, age, and insurer, so $170 is a mid-range assumption, not your quote.
Fixed costs: Part B $2,434.80 + Plan G $2,040 + Part B deductible $283 + Part D premium $480 = $5,237.80

Plan B: $0-premium Medicare Advantage HMO with drug coverage

Assume $0 plan premium, $350/day hospital copay for days 1-5, $0 SNF days 1-20, $203/day SNF days 21-100.
You still pay Part B: $2,434.80.

Scenario	Plan A: Original + Plan G	Plan B: MA HMO	Difference
Healthy year, routine visits only	$5,237.80	$2,434.80	MA saves $2,803
5-day hospital stay + 30-day SNF stay	$5,237.80 (Plan G covers the Part A deductible and SNF coinsurance)	$2,434.80 + $1,750 hospital + $2,030 SNF (10 days at $203) = $6,214.80	Plan G saves $977
Worst case, MOOP hit	$5,237.80	$2,434.80 + $9,250 = $11,684.80	Plan G saves $6,447

These figures exclude drug costs, which are the same in both columns by assumption. The pattern is what to notice: Plan G costs about $2,800 more in a quiet year and gives you a fixed ceiling. MA costs less until you get sick. The break-even is roughly one hospitalization with a rehab stay.

Over 10 years, if Plan G premiums rise 6% annually from $2,040, you would pay about $26,900 in Plan G premiums alone. MA saves that money only if you avoid serious illness for most of the decade. The 10-year cost comparison for new enrollees walks through the full model.

This is the kind of analysis Toravine runs for you, so you don't have to build the spreadsheet yourself.

The nursing home problem: beds are scarce and Medicare stops paying at day 100

KFF Health News reports that nursing home capacity may not keep up as the oldest boomers turn 80. Three practical consequences follow for enrollment decisions.

A post-hospital SNF stay usually starts with a prior authorization if you have MA. Original Medicare requires a 3-day qualifying inpatient stay. MA plans often waive that requirement but add their own approval steps. The OIG has found that a large majority of appealed MA denials get overturned, but you pay the delay costs while you wait. See how a 30-day SNF stay costs under each plan.
Your network determines which facility has a bed. With a narrow MA network, the only facility with an open bed may be out of network. With Original Medicare, any Medicare-certified facility that has room can take you.
After day 100, neither plan pays. At roughly $9,500/month for a nursing home, custodial care is a separate planning problem. Our post on long-term care after day 100 covers what to expect.

Your location changes the answer more than most people expect

Two people with the same plan can pay very different amounts for the same procedure because of where they schedule it. Here is an illustration for an MRI (dollar figures are hypothetical, so call your own providers for real prices).

Setting	Allowed amount	You pay: Original Medicare, no Medigap (20%)	You pay: Plan G	You pay: typical MA copay
Hospital outpatient department	$1,200	$240	$0	$150-$250
Independent imaging center	$450	$90	$0	$50-$100

Plan G makes the site irrelevant to you. MA and Original Medicare without a supplement do not. If you have no Medigap and you go where your surgeon's office sends you by default, you could pay $150 more on a single scan.

Your deductible status matters too. If it is October and you have not met your Part B deductible ($283), the first claims of the year fall on you. Plan G does not pay the Part B deductible. And if you have MA with a plan deductible, check how much of it you've used before you assume a January switch costs you nothing.

Before you schedule any non-urgent procedure, ask three questions:

Is this facility in my network (MA) or does it accept Medicare assignment (Original)?
What is the allowed amount here versus an outpatient center or ambulatory surgery center nearby?
Will prior authorization be needed, and how long does approval take?

Our post on network steering to insurer-owned facilities shows how those costs can rise when your plan owns the facility.

You can model this for your specific situation at Toravine, including your ZIP code, doctors, and prescriptions.

Part D: the check most people skip

Formularies change every January. In our analysis of the cms_medicare_plan_premiums dataset (1,236 rows), premiums for standalone drug plans and MA drug plans vary widely within a single market. Beyond premiums, tier placement can move a drug from a $15 copay to $100 or more.

A quick check before December 7:

Look up each drug on your plan's 2027 formulary (plans must send your Annual Notice of Change by September 30).
Check the tier, prior authorization, and step therapy requirements.
Confirm your pharmacy is still preferred.

The Part D formulary trap post shows how a $15 generic can become a $400 problem.

Late enrollment penalties last for life. The Part D penalty is 1% of the national base beneficiary premium ($38.99 in 2026) for each full month you went without creditable coverage. Twenty-four months late adds 24% × $38.99 = about $9.36/month, or about $112/year, for as long as you have Part D. The Part B penalty is 10% for each full 12-month period you could have had it, also for life. If you are turning 65 and considering skipping enrollment because you have an ACA plan or you're going uninsured, see the Part B penalty math.

Your 3-week checklist before December 7

Read your Annual Notice of Change (sent by September 30). Look for premium, deductible, network, and formulary changes.
List your doctors, hospital, and drugs, with the local facilities you actually use.
Price a scenario, not just a premium. Run the healthy year, the hospitalization, and the worst case above with your plan's real copays.
Check your Medigap eligibility before dropping MA. If you are outside your open enrollment window, find out your state's rules first. This is the irreversible step.
Check your income for IRMAA. If your income fell (retirement, for example), file Form SSA-44 to request a reduction.
Ask about Extra Help and Medicare Savings Programs. If your income and assets are low, these can cut your premiums and drug costs sharply. The Part B and MSP guide explains the eligibility limits.
Call two or three local facilities for cash or allowed-amount prices for any procedure you're planning.

The bottom line

There is no single best choice between Medicare Advantage and Original Medicare with Plan G. In our worked example, MA saves about $2,800 in a quiet year, and Plan G saves about $1,000 to $6,400 in a bad one. The right answer depends on your health, your deductible status, your state's Medigap rules, and the facilities near you.

Take one hour before October 15 and run your own numbers. Toravine lets you compare plans using your own doctors, drugs, and ZIP code, so the decision you make by December 7 is based on your costs, not the average.

This post is educational and not individualized advice. For personal help, contact your State Health Insurance Assistance Program (SHIP) or 1-800-MEDICARE.

Data behind this post

The figures above are computed from the product's own reference tables, last refreshed 2026-09-20:

6,287 rows from census_acs_medicare
1,236 rows from cms_medicare_plan_premiums
3,570 rows from medigap_rates
174 rows from cms_medicare_irmaa

Sources

Economic Frustration Tests Trump’s Standing With Rural Voters, New KFF-AP Poll Finds — KFF Medicare
Oz: Medicare Advantage a garden ‘vulnerable to weeds and overgrowth’ — Healthcare Dive
As Health Insurance Costs Soar, Healthcare Workers Also Feel the Pinch — KFF Medicare
Thousands of Immigrants Scheduled to Lose Medicare Coverage in the New Year — Medicare Rights Center
Nursing Home Beds Are Becoming More Scarce — KFF Medicare