Medicare Planning Complete Guide

An honest framework for the decisions at hand. Not tax or investment advice — your specifics matter.

The IRMAA cliffs

• Medicare Part B and Part D premiums are income-based for higher earners under IRC § 1839(i) and § 1860D-13(a).¹
• 2026 IRMAA tiers (premiums based on 2024 MAGI, 2-year lookback): starts at $109,000 single / $218,000 MFJ.²
• Base Part B premium 2026: $202.90/month.² Tier surcharges add $81.20–$487.00/mo (Part B) + $14.50–$91.00/mo (Part D).
• Cliff, not ramp: $1 over a threshold = full tier surcharge. Planning to stay $1 under is real.
• Per-person: married couples pay two IRMAAs if both are on Medicare — effectively double the surcharge burden.

Two-year MAGI lookback

• 2024 premiums use 2022 MAGI.
• 2026 premiums use 2024 MAGI.
• Planning horizon: what you earn this year sets your Medicare premiums in two years.
• Retirees with flexibility (Roth conversions, capital gains, RMDs) can manage this year-by-year.

IRMAA appeal via SSA-44

• Form SSA-44 allows appeal for specific life-event MAGI changes.³
• Qualifying life-changing events: marriage, divorce/annulment, death of spouse, work stoppage, work reduction, loss of income-producing property (involuntary, e.g., disaster), loss/termination of pension income, or employer-plan settlement due to plan termination/bankruptcy.
• Normal retirement (work stoppage) IS a qualifying event — use this in your retirement year if your MAGI is expected to drop below threshold.
• File SSA-44 with estimated current-year MAGI and supporting documentation. SSA recalculates IRMAA based on projected income.

Roth conversion + IRMAA tradeoff

• Converting traditional IRA to Roth is often optimal — but large conversions can push into higher IRMAA brackets.
• Strategy: convert up to the IRMAA cliff (stay $1 under). Partial conversions over multiple years avoid the tier jump.
• Exception: conversion in the two years before Medicare eligibility (63-64) doesn't affect IRMAA since you're not yet on Medicare. Worth front-loading here.

Medicare Advantage vs Original + Medigap

• Medicare Advantage (Part C): bundled HMO/PPO; low/no monthly premium; often includes dental/vision/hearing; network restrictions; prior-authorization requirements common.
• Original Medicare + Medigap (Supplement): fee-for-service; any Medicare-accepting provider; Medigap covers the 20% Medicare coinsurance gap; monthly premium ~$100–$400 depending on plan letter and location.
• Medigap Open Enrollment Period: 6-month window starting when you are 65+ AND enrolled in Part B. During this window, Medigap rates are guaranteed-issue with no medical underwriting.⁴ After this window closes, switching can be denied based on health (except in a few states like NY, CT, ME, MA that have year-round guaranteed issue).
• Most specialty care (cancer, complex procedures): Original Medicare + Medigap is typically preferred. Routine care: either model works.
• Warning: the MA → Medigap switch is generally subject to underwriting after the initial 12-month trial right.⁵ This effectively locks in a decision for many beneficiaries with health conditions.

Working past 65 with employer coverage

• Large employer (20+ employees): employer coverage is primary payer under Medicare Secondary Payer rules; Medicare is secondary and optional. Often better to delay Medicare Part B enrollment.⁶
• Small employer (<20): Medicare is primary. Must enroll in A + B at 65 or face late-enrollment penalties (lifetime 10% per 12-month period of delay for Part B).
• HSA consideration: Medicare enrollment (including Part A) ends HSA-eligibility under IRC § 223(b)(7). If maximizing HSA contributions matters, delay Medicare enrollment AND delay Social Security (which triggers automatic Part A enrollment 6 months retroactively).⁷
• Special Enrollment Period: 8 months after employer-group coverage ends to enroll without penalty.⁸

Sources

1. 42 U.S.C. § 1395r (Social Security Act § 1839) — Part B Premium Formula and IRMAA.
2. Kiplinger — 2026 Medicare IRMAA Brackets and Surcharges. Cross-checked with CMS 2026 Medicare Premiums Fact Sheet.
3. SSA Form SSA-44 — Medicare IRMAA Life-Changing Event.
4. Medicare.gov — Medigap Open Enrollment Period.
5. Medicare.gov — Guaranteed Issue Rights (Trial Right, 12-month switch back from MA).
6. CMS — Medicare Secondary Payer Rules. Large employer defined as 20+ for retirees.
7. IRC § 223(b)(7) — HSA Ineligibility When Enrolled in Medicare.
8. Medicare.gov — Special Enrollment Periods (8-month SEP after employer coverage ends).

IRMAA thresholds and Medicare premiums verified against CMS 2026 publications. Appeal via Form SSA-44 can significantly reduce surcharges in retirement transition years.