How do IRMAA thresholds change year to year and where can retirees find official future values?
Executive summary
IRMAA thresholds are adjusted annually for inflation for most brackets, using a CPI‑U comparison calculated each fall, and beneficiaries are assigned surcharges based on their MAGI from two years prior (the “two‑year lag”)—creating sharp “cliffs” where even $1 can trigger higher premiums [1] [2] [3]. Official, authoritative values and the SSA’s IRMAA tables are published by the Social Security Administration (POMS and SSA notices) each year after the COLA/consumer‑price calculations, and retirees should consult those SSA publications for future, finalized thresholds [2] [1].
1. How thresholds change year to year: inflation indexing, a two‑year lag, and cliff effects
Most IRMAA brackets are indexed annually: each fall the SSA updates the first four IRMAA brackets by comparing two CPI‑U averages (the 12 months ending the most recent August versus the previous 12‑month period) and applies that percentage change as the inflation adjustment, producing small, incremental increases in most years [1]. Because IRMAA is determined from Modified Adjusted Gross Income (MAGI) reported two years earlier, beneficiaries pay based on a lagged income measure—so 2024 tax returns determine 2026 IRMAA liability—adding planning complexity [4] [3]. The structure is a set of statutory percentage tables: higher MAGI ranges correspond to higher Part B and Part D surcharges, and the system uses “cliffs” where exceeding a threshold by as little as $1 moves a person into a higher surcharge tier [2] [4] [3].
2. Which brackets move and which don’t: the top tier exception and recent practice
Most commentary and the SSA rules make clear that the first four brackets receive the inflation adjustment each autumn, while the top IRMAA tier has been subject to statutory limits and, in at least some reporting, has been frozen through 2028—meaning the top cutoff may not rise with inflation even when other brackets do, which can compress taxpayers into higher relative burdens over time [4] [5]. Because those adjustments are generally modest in years of low CPI‑U growth, modest portfolio gains, RMDs, or one‑time taxable events can still push retirees across a bracket despite the indexing [1].
3. Practical consequences: sudden premium increases and the scale of surcharges
The cliff design and percentage surcharge tables can produce sudden and meaningful increases in annual Medicare costs: recent reporting shows IRMAA surcharges added thousands of dollars annually to Part B and Part D bills, and the maximum combined IRMAA totals rose from 2025 to 2026 in published estimates [6]. The statutory sliding‑scale tables in SSA policy show the percentage multipliers that determine how much more higher‑income beneficiaries pay compared with the standard premium, and providers reiterate that Part B IRMAA is generally deducted from Social Security benefits while Part D IRMAA is billed separately [2] [6] [7].
4. Where retirees can find official, future values and finalized thresholds
The authoritative source for IRMAA sliding‑scale tables and official thresholds is the Social Security Administration’s policy and releases—specifically the POMS IRMAA sliding scale documentation and SSA annual IRMAA notices that incorporate the CPI‑U adjustment each fall; those are the places to watch for finalized numbers for upcoming years [2] [1]. Financial press and advisory sites compile and explain the published values (examples cited include Kiplinger, NerdWallet, and advisors’ analyses) but those secondary outlets rely on SSA releases for the final thresholds [3] [8] [9].
5. How retirees should plan and when to verify numbers
Because IRMAA is based on MAGI two years prior and brackets can shift modestly each fall, retirees are advised to project taxable income, watch RMD timing and Roth conversion strategies, and—if income drops due to retirement or other life events—use SSA’s life‑changing event form (SSA‑44) to seek reconsideration; appeal and redetermination processes are explicitly available [10]. While many advisory pieces encourage preemptive tax planning to avoid crossing thresholds, retirees should verify any planning assumptions against the SSA’s official POMS tables and the SSA’s annual IRMAA notices when they are released [1] [2].