IRMAA Calculator 2026: Avoid the Medicare Premium Surcharge That Costs Retirees $4,600/Year
IRMAA adds $96.40 to $578.30 per month per person to your Medicare Part B premium when income exceeds $109,000 (single) or $218,000 (joint). QuantCalc models two-factor IRMAA with separate CPI and medical inflation rates across your full retirement, showing how Roth conversions and withdrawal timing prevent IRMAA spikes before they hit.
What IRMAA Is and Why It Matters
IRMAA — the Income-Related Monthly Adjustment Amount — is a Medicare surcharge that affects roughly 8% of enrollees. Cross the income threshold by even one dollar and you pay the full surcharge for that tier. There is no gradual phase-in.
The 2026 IRMAA brackets for Medicare Part B:
| Single MAGI | Joint MAGI | Monthly Surcharge (per person) |
|---|---|---|
| Up to $109,000 | Up to $218,000 | $0 (standard premium) |
| $109,001 - $137,000 | $218,001 - $274,000 | +$96.40/month |
| $137,001 - $171,000 | $274,001 - $342,000 | +$240.90/month |
| $171,001 - $214,000 | $342,001 - $428,000 | +$385.40/month |
| $214,001 - $500,000 | $428,001 - $750,000 | +$529.90/month |
| Over $500,000 | Over $750,000 | +$578.30/month |
For a couple in the second tier, that is $2,314 per year in extra premiums. At the top tier: $13,879 per year — money that comes directly out of your retirement income.
The Two-Year Lookback Problem
IRMAA is determined by your Modified Adjusted Gross Income from two years prior. Your 2026 Medicare premiums are based on your 2024 tax return. This means the Roth conversion you did in 2024 — or the capital gain you took, or the RMD you received — is setting your Medicare costs right now.
Most retirees discover IRMAA after the fact. Planning requires looking forward: what will my MAGI be in each year, and how does that cascade into Medicare premiums two years later?
Why Most Calculators Get IRMAA Wrong
Standard retirement calculators either ignore IRMAA entirely or apply a single inflation rate to both MAGI thresholds and premium amounts. This produces misleading results.
The reality is that IRMAA has two inflation components:
- MAGI thresholds adjust by CPI (~2.5% historically)
- Premium surcharges inflate at the medical inflation rate (~5% historically)
Over a 30-year retirement, this divergence is massive. A surcharge that costs $2,314/year today costs $9,950/year in year 20 under medical inflation — but only $4,800/year if you incorrectly assume CPI for both. That is a $154,500 lifetime error for one couple.
QuantCalc decouples these rates. The medicareInflationRate parameter applies medical-specific inflation to premium amounts while CPI governs threshold adjustments.
Strategic IRMAA Avoidance
The primary lever is Roth conversion timing. Convert too much in one year and you spike your MAGI into a higher IRMAA tier two years later. Convert too little and you face larger RMDs that push you into IRMAA permanently after 73.
QuantCalc's Roth conversion optimizer offers two modes:
- Fixed dollar conversion: Convert a set amount per year (e.g., $50,000/year from age 60-72)
- Bracket-fill-to-ceiling: Automatically converts up to the IRMAA threshold OR tax bracket ceiling, whichever is lower. Uses 85% of estimated Social Security benefits in the MAGI calculation.
Both modes run across 10,000 Monte Carlo scenarios with stochastic market returns, so you see the probability of IRMAA exposure across thousands of possible futures.
IRMAA and ACA: The Dual Cliff
Early retirees face a unique challenge: before 65, keeping MAGI below the ACA subsidy cliff (400% FPL) saves $15,000+/year in health insurance. After 65, keeping MAGI below IRMAA thresholds saves $2,300-$13,800/year in Medicare premiums. QuantCalc models both cliffs simultaneously, optimizing withdrawal strategy across the entire retirement timeline.
Frequently Asked Questions
What is IRMAA?
IRMAA (Income-Related Monthly Adjustment Amount) is a Medicare surcharge added to your Part B and Part D premiums when your Modified Adjusted Gross Income exceeds $109,000 (single) or $218,000 (joint). It is determined by your tax return from two years prior.
How is IRMAA calculated?
IRMAA uses your Modified Adjusted Gross Income (MAGI) from two years prior. For 2026 premiums, your 2024 MAGI determines your tier. Surcharges range from $96.40 to $578.30 per month per person for Part B, with additional Part D surcharges.
Can I avoid IRMAA with Roth conversions?
Yes. Strategic Roth conversions before age 73 can reduce future Required Minimum Distributions that push you into IRMAA tiers. QuantCalc's BRACKET_FILL optimizer automatically caps conversions below IRMAA thresholds while maximizing tax bracket usage.
What are the 2026 IRMAA brackets?
2026 IRMAA brackets for single filers: up to $109,000 (no surcharge), $109,001-$137,000 (+$96.40/mo), $137,001-$171,000 (+$240.90/mo), $171,001-$214,000 (+$385.40/mo), $214,001-$500,000 (+$529.90/mo), over $500,000 (+$578.30/mo). Joint filers have approximately double thresholds.
Plan Your IRMAA Strategy Across 10,000 Scenarios
Run your IRMAA scenario with two-factor inflation (CPI thresholds + medical premium growth), Roth conversion optimizer, and 10,000 Monte Carlo simulations. See the probability of IRMAA exposure in every year of your retirement.
PRO unlocks: Two-factor IRMAA modeling, Roth conversion optimizer (FIXED + BRACKET_FILL), 10,000 simulations, institutional forecasts, PDF reports.