For retirees enrolled in Medicare, one of the quietest but most expensive tax-like surcharges in the system is IRMAA — the Income-Related Monthly Adjustment Amount that increases Part B and Part D premiums for higher-income beneficiaries. The 2026 brackets are now in effect, and the math is harsher than many retirees realize: a single dollar of extra income can push a household into the next tier and cost more than $2,000 a year in additional premiums.
How the 2026 Brackets Look
According to Kiplinger and CMS-published figures, the standard 2026 Part B premium is $202.90 per month. Above that base, IRMAA layers on five surcharge tiers that scale with modified adjusted gross income (MAGI):
- Tier 1 begins at $109,000 MAGI for single filers and $218,000 for married filing jointly.
- Tier 5, the highest, starts at $500,000 single and $750,000 joint.
- Combined with the base, the all-in Part B premium ranges from $202.90 to roughly $689.90 per month in 2026.
- Part D surcharges add another $14.50 to $91.00 per month on top of the drug plan's own premium.
Brackets ticked up roughly 3% from 2025, while top-tier surcharge amounts rose by closer to 9% — meaning the cost of crossing a threshold has grown faster than the income limits that define them.
The Two-Year Lookback
IRMAA is calculated using MAGI from two tax years prior. The 2026 surcharges are set by 2024 tax returns. That lag matters for two reasons:
- Retirees who had a one-time income event in 2024 — a property sale, a large Roth conversion, an inherited IRA distribution — are paying for it in 2026, even if 2026 income is modest.
- Planning decisions made today affect the 2028 IRMAA bill, not next year's. That is roughly the same horizon over which Roth conversions and capital gains harvesting decisions are evaluated.
Why It Is Called a Cliff
Unlike federal income tax, which uses graduated brackets, IRMAA tiers are all-or-nothing. As analyses from Range and Income Laboratory point out, going $1 over a threshold triggers the full surcharge for the entire tier.
A married couple just $1 over the Tier 1 cutoff of $218,000 pays roughly $2,297 more in annual Medicare premiums than a couple at $217,999 — for the same standard of living and the same care.
The Roth Conversion Trap
The most common 2026 IRMAA trigger is a well-intentioned Roth conversion. Converting a Traditional IRA or 401(k) to a Roth is widely recommended for retirees in their 60s, before required minimum distributions (RMDs) begin at age 73 or 75. But the converted amount counts toward MAGI in the year it occurs.
A retiree who converts "to the top of the 24% bracket" without checking IRMAA brackets can easily overshoot a Medicare threshold and erase part of the tax savings. Conversely, skipping conversions to stay under a threshold can leave the pretax IRA to grow into a larger RMD — and a larger IRMAA surcharge — later.
Practical Strategies
- Project MAGI before December 31. Add up wages, Social Security, pensions, interest, dividends, capital gains distributions, and any planned Roth conversion. Subtract HSA contributions and pre-tax retirement contributions.
- Build a safety margin. Advisors typically suggest staying $2,000 to $5,000 below the next IRMAA threshold to absorb late-year mutual fund capital gains distributions, which are rarely predictable.
- Ladder Roth conversions. Filling each year's bracket up to — but not over — a chosen IRMAA tier across several years can convert large pretax balances without ever triggering the cliff.
- Coordinate with Qualified Charitable Distributions (QCDs). Once eligible at 70½, QCDs reduce MAGI and can keep retirees under an IRMAA tier while satisfying RMDs.
- File Form SSA-44 after a "life-changing event" such as retirement, the death of a spouse, or a work stoppage. Social Security can recalculate IRMAA using current-year income instead of the two-year-old return.
The Bigger Picture
IRMAA is not the only retirement planning lever, and avoiding it is not the goal — minimizing lifetime taxes is. Sometimes paying one year of IRMAA to complete a large Roth conversion is the right move; sometimes deferring is. What matters is that the decision is made with full visibility into the cliff, not stumbled into in April when the tax return is filed.
For retirees in or near the IRMAA zone, the 2026 brackets are a good reminder that retirement tax planning extends well beyond income tax rates. The premium line on the Medicare bill is, in many households, a tax bracket of its own.
Sources: Kiplinger, The Finance Buff, Centers for Medicare & Medicaid Services, Range, Income Laboratory