What are the IRMAA MAGI thresholds for 2025 and how much could a Roth conversion push me into a higher bracket?
Executive summary
For 2025, IRMAA begins at MAGI above $106,000 for single filers and $212,000 for married filing jointly; the thresholds are based on your 2023 tax return and surcharges apply to both Part B and Part D [1] [2] [3]. Large Roth conversions count as taxable income in the conversion year and therefore raise MAGI for IRMAA’s two‑year lookback, meaning a single big conversion can push you into a higher IRMAA tier and materially increase Part B/Part D monthly premiums [4] [5] [6].
1. What the 2025 IRMAA thresholds actually are
Medicare determines IRMAA from your MAGI two years earlier, so 2025 surcharges are computed from your 2023 tax return. The income thresholds for 2025 start at $106,000 for individual filers and $212,000 for joint filers; crossing those lines triggers the first IRMAA surcharge and higher bands follow above that [2] [3] [1].
2. How much the surcharge can cost you in dollars
The IRMAA surcharge changes your monthly Part B and Part D bills by bracket. For 2025, examples in reporting show Part B surcharges that can raise annual costs by hundreds to several thousand dollars and Part D surcharges that range from a few dozen to over a thousand annually depending on bracket — one compilation put Part B extra costs between $888 and $5,326.80 per year and Part D extra costs between $164.40 and $1,029.60 per year across tiers [7] [8]. Exact surcharge amounts depend on which IRMAA tier your MAGI falls into [8].
3. Why a Roth conversion changes the IRMAA picture
A Roth conversion is taxed as ordinary income in the year of conversion and therefore increases your MAGI for that tax year, which the SSA uses two years later to set IRMAA [5] [9]. Multiple advisers and calculators warn that even a one‑time conversion large enough to tip MAGI over a bracket edge will produce the full higher surcharge — IRMAA works like a cliff: $1 over a threshold can cause the higher monthly premium to apply [4] [10].
4. Quantifying the effect: simple scenarios from reporting
Published examples show the mechanics. One illustration: converting $100,000 when your pre‑conversion MAGI is $80,000 could raise a single filer’s MAGI to $180,000 and move them into a much higher IRMAA bracket, increasing Part B monthly premium materially — e.g., a Part B premium jump to about $480.90 monthly in that scenario, equal to roughly $1,330.80 more per year compared with the lower premium [4]. Forbes and planning firms repeat that large conversions in a single year can raise Part B/D costs for the IRMAA year two years later [11] [12].
5. Tradeoffs: short‑term pain vs. long‑term gain
Authors and advisors frame Roth conversions as a tradeoff: you pay tax now (and possibly higher IRMAA later) to reduce future RMDs and tax exposure, and distributions from Roth IRAs do not count toward MAGI in later years [10] [9]. Some planners argue a conversion that temporarily raises IRMAA might be worth it if future years’ MAGI falls and long‑term RMD reduction prevents repeated surcharges [11] [10].
6. Practical planning rules and caveats
Sources recommend: model conversions against IRMAA thresholds, spread conversions over multiple years to avoid cliff effects, and consider charitable qualified charitable distributions (QCDs) or other MAGI‑reducing moves in high‑conversion years [4] [10] [7]. SSA allows life‑changing event appeals to use more recent MAGI in certain cases, but routine conversions don’t qualify; see SSA Form SSA‑44 for procedural details [13].
7. Limits of available reporting and disagreements to note
Most sources agree on the core facts: 2025 thresholds, two‑year lookback, Roth conversions add to MAGI and can trigger IRMAA [2] [5] [6]. Where articles differ is emphasis and dollar examples: some vendors show slightly different surcharge totals or use illustrative Part B numbers; those differences reflect different snapshot dates, rounding and whether they include base Part B premium in totals [8] [7] [4]. Available sources do not mention your personal numbers or give bespoke modeling — a tax pro or scenario run is necessary for precise planning.
8. Bottom line for readers deciding whether to convert
If your 2023 MAGI would be pushed above a 2025 IRMAA threshold by a Roth conversion, expect the SSA to treat that higher MAGI as the basis for IRMAA two years later and to impose the full higher surcharge for the applicable year. Plan conversions across years or model smaller ladders so you stay below the cliff if avoiding higher Medicare premiums is a priority [4] [10] [7].