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Medicare Open Enrollment: Part B & IRMAA Brackets

CMS Medicare guide for 2026-2027: Calculate Part B & Part D IRMAA income surcharges, compare Medigap Plan G vs Advantage, and check the $2,000 drug cap.

GBy GST Munshi US Quantitative & Statutory Desk•Published: September 2026•17 min read
Audited against Centers for Medicare & Medicaid Services (CMS) Fact Sheets, Social Security Act § 1839(i) (IRMAA) & Inflation Reduction Act Part D Cap Rules
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Medicare Open Enrollment: Part B & IRMAA Brackets
Medicare IRMAA & Cost Calculator — Verified US Statutory & Quantitative Analysis ($ USD)
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Table of Contents (8 Sections)
Quick Answer & Key Takeaways

What are the key Medicare Open Enrollment rules, IRMAA brackets, and Part D out-of-pocket caps?

Medicare's Annual Election Period (Open Enrollment) runs every year from October 15 through December 7, with coverage changes taking effect on January 1. Under federal law, Medicare Part D prescription drug plans feature a hard $2,000–$2,100 annual out-of-pocket cap (eliminating the historic 'donut hole'). Retirees with Modified Adjusted Gross Income (MAGI) above $106,000 (Single) or $212,000 (Married Filing Jointly) on their 2-year lookback IRS tax return pay an Income-Related Monthly Adjustment Amount (IRMAA) surcharge on top of standard Part B and Part D premiums.

Annual Election Period (AEP): October 15 – December 7 (Switch Part D drug plans or Medicare Advantage)
Part D Out-of-Pocket Ceiling: Capped at $2,000+ indexed annually; 100% catastrophic coverage above cap
IRMAA 2-Year Lookback: 2026 premiums use 2024 IRS MAGI; 2027 premiums use 2025 IRS MAGI
Form SSA-44 IRMAA Appeal: File if your income dropped due to work stoppage/retirement, divorce, or spouse's death
CMS Medicare Part B & Part D IRMAA Surcharge Calculator ($ USD)

Check Your 2-Year Lookback MAGI & Monthly Medicare IRMAA Tier

Estimated Monthly Part B + Part D IRMAA Cost
$405.30 / month
IRMAA Surcharge Triggered — File Form SSA-44 if you had a retirement life-changing event.

1Original Medicare (Part A + B + Medigap Plan G) vs Medicare Advantage (Part C)

Choosing between Original Medicare paired with a Medigap supplement (such as Plan G) and a private Medicare Advantage (Part C) HMO/PPO plan is the most consequential healthcare decision US retirees make at age 65.

Original Medicare + Medigap Plan G allows you to see any doctor or specialist nationwide who accepts Medicare (including premier cancer centers like Mayo Clinic and MD Anderson) with zero network referrals and zero prior authorizations, paying only the small annual Part B deductible (~$257). Conversely, Medicare Advantage plans advertise $0 monthly premiums and dental/vision perks, but enforce strict HMO/PPO networks, prior authorizations, and annual out-of-pocket maximums up to $8,850–$9,350.

Original Medicare + Medigap Plan G vs Medicare Advantage (Part C) Comparison

FeatureOriginal Medicare + Medigap Plan GMedicare Advantage (Part C HMO/PPO)
Doctor & Hospital AccessAny US Provider Accepting Medicare NationwideRestricted to Plan's Local HMO/PPO Network
Prior Authorization Required?Rarely (Covered if Medically Necessary under CMS)Frequent for MRI, Surgery, Rehab & Specialist Care
Monthly Supplement Premium$130 – $240/mo (Plus Part B & Part D Premium)$0 – $60/mo (Plus Base Part B Premium)
Maximum Annual Medical Out-of-Pocket~$257 (Only the Annual Part B Deductible!)Up to $8,850 – $9,350 In-Network
Switching Back Later?Guaranteed Issue Only in 6-Month Initial Window (Medical Underwriting Applies Later in Most States)Can Switch Annually Oct 15 – Dec 7

4-Step Medicare Enrollment & IRMAA Surcharge Defense Blueprint

STEP 01

Lock In Medigap Plan G During Your 6-Month Guaranteed Issue Window

Your 6-month Medigap Open Enrollment starts the month you turn 65 and enroll in Part B—insurers cannot deny you or charge more for pre-existing conditions.

STEP 02

Re-Shop Your Part D Prescription Drug Plan Every October 15 – December 7

Drug formularies and preferred pharmacy tiers change every January. Run your exact medication list on Medicare.gov Plan Finder every autumn.

STEP 03

Stop HSA Contributions 6 Months Before Applying for Medicare

Medicare Part A coverage is retroactive up to 6 months (not earlier than age 65). Contributing to an HSA during retroactive Part A coverage triggers a 6% IRS excise penalty.

STEP 04

File Form SSA-44 Immediately Upon Retirement to Waive IRMAA

Do not overpay IRMAA based on your peak working income from 2 years ago. Submit Form SSA-44 citing 'Work Stoppage' or 'Work Reduction' to reset your premium to the base tier.

Curated Expert Video Walkthroughs & Wall Street Briefings

CMS Medicare.gov: Medicare Part A, B, C & D Explained Simply
Watch on YouTube
Medicare Part A, B, C & D Explained Simply
Click to Play Video
Medicare Part A, B, C & D Explained SimplyOpen in App
Abt Insurance Agency: Medigap Plan G vs Medicare Advantage: The Truth
Watch on YouTube
Medigap Plan G vs Medicare Advantage: The Truth
Click to Play Video
Medigap Plan G vs Medicare Advantage: The TruthOpen in App
Medicare School: How to Appeal Medicare IRMAA Surcharges with Form SSA-44
Watch on YouTube
How to Appeal Medicare IRMAA Surcharges with Form SSA-44
Click to Play Video
How to Appeal Medicare IRMAA Surcharges with Form SSA-44Open in App
CNBC Television: Medicare Part D $2,000 Out-of-Pocket Cap Explained
Watch on YouTube
Medicare Part D $2,000 Out-of-Pocket Cap Explained
Click to Play Video
Medicare Part D $2,000 Out-of-Pocket Cap ExplainedOpen in App

Frequently Asked Questions (Verified Statutory Answers)

Q1: Can I switch from Medicare Advantage back to Medigap Plan G five years into retirement?

In most US states (except year-round guaranteed-issue states like New York, Connecticut, Massachusetts, and Maine), switching from Medicare Advantage to a Medigap policy after your initial 12-month trial right requires passing medical underwriting—meaning insurers can deny your application if you have developed chronic health conditions.

Q2: What is the Medicare Part B late enrollment penalty?

If you do not sign up for Part B when first eligible at age 65 and lack qualifying active employer group coverage (from a company with 20+ employees), your Part B monthly premium permanently increases by 10% for every full 12-month period you delayed.

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