How have IRMAA bracket thresholds changed over the last five years and what caused the top bracket freeze until 2028?
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Executive summary
Over the past five years IRMAA income thresholds have inched upward overall, driven by inflation indexing and a statutory two‑year lookback that ties surcharges to past MAGI, producing modest annual threshold increases in 2024–2026 that still leave many beneficiaries vulnerable to “cliff” hikes if income creeps above a line by even a dollar [1] [2] [3]. Multiple financial and Medicare‑focused outlets report that the highest IRMAA bracket has been held at a fixed threshold through 2028, but the reporting does not definitively identify a single statutory or regulatory action as the cause, leaving room for interpretation and alternative explanations [4] [5].
1. How the brackets moved — a five‑year snapshot
From 2021 through 2025 the IRMAA thresholds rose, sometimes substantially and sometimes only slightly, because the program began indexing thresholds for inflation (CPI‑U) starting in 2020 and then adjusted them annually thereafter; for example the single‑filer threshold moved to $103,000 in 2024 and $106,000 in 2025 (or $212,000 for couples in 2025) according to Medicare and industry reporting [1] [2] [6]. Analysts and advisers tracked similar incremental increases into 2026 — NerdWallet reports a $109,000 individual threshold for 2026 — and niche sites that project future brackets note the same upward drift that reflects either measured CPI changes or modest inflation projections [7] [8].
2. The mechanics behind annual changes — CPI linkage and the two‑year lookback
IRMAA thresholds are adjusted using a CPI‑U formula and applied to beneficiaries based on modified adjusted gross income (MAGI) from two years earlier, so what someone paid in 2025 is tied to their 2023 tax return; that two‑year lag plus CPI indexing is why relatively small CPI readings produce modest threshold shifts and why tax‑planning moves such as Roth conversions can abruptly push someone into a higher surcharge tier [3] [6] [4]. The “cliff” design means exceeding a threshold by a single dollar triggers the next surcharge level, a characteristic emphasized repeatedly in reporting and consumer guidance [3] [9].
3. What reporting says about the top bracket freeze through 2028
Several advisory and Medicare‑focused sources explicitly state the top IRMAA bracket has been frozen through 2028, and some tie that to the Trustees’ multi‑year projections or to administrative updates that left the top tier unchanged in the official sliding‑scale tables [4] [5] [10]. Those sources portray the freeze as a concrete scheduling fact — the top tier’s income threshold will not rise again through 2028 — but they stop short of pointing to a named statute or a single regulatory rule that instituted the freeze, leaving the causal chain opaque in the public reporting [4] [5].
4. Why the freeze matters — competing explanations and reporting limits
The freeze is consequential because it preserves a relatively low cap on the highest tier even as the rest of the schedule inches upward, concentrating more beneficiaries into the maximum surcharge bracket if incomes rise; that outcome is consistent with the Trustees’ framework for projecting IRMAA through 2028 and with commentary that modest CPI increases have produced only small threshold moves elsewhere [10] [8]. However, the sources reviewed do not provide definitive documentary evidence that the freeze is the result of explicit congressional language, a discrete administrative rule, or simply the Trustees’ projection methodology — alternative explanations include an intentional policy choice to maintain progressivity, a temporary administrative freeze to simplify budgeting, or the arithmetic result of using a specific CPI‑based formula — and the reporting does not adjudicate among those possibilities [4] [5].
5. Practical implications and the policy angle
Practically, beneficiaries and planners should treat the freeze as a real constraint in planning models: because IRMAA is a cliff and thresholds are indexed but not automatically large, small income changes (Roth conversions, capital gains, retirement distributions) can produce outsized premium bills, which is why advisors and outlets urge year‑end planning and monitoring of CPI‑driven threshold updates [8] [9]. From a policy perspective, freezing the top bracket preserves higher relative contributions from wealthier beneficiaries but also invites scrutiny about fairness and transparency because public reporting has not clearly documented the statutory or regulatory mechanism that produced the 2028 freeze [4] [5].