Can a Roth conversion at 63 increase Medicare premiums at 65?
Susan is a fictional 63-year-old retiree comparing no conversion with one-time $50,000 and $100,000 conversions. The conversion income is measured two years later when Medicare evaluates her age-65 IRMAA tier.
Written by James Wilson · Calculated and reviewed August 3, 2026
Starting assumptions
| Traditional / Roth / taxable | $1,100,000 / $75,000 / $125,000 |
| First-year spending | $72,000, including healthcare |
| Filing status | Single, Oregon |
| Social Security | Claim at 67; $3,400 per month in 2026 dollars |
| Medicare | Simple Deterministic model; standard Part B and calculated IRMAA |
| Projection | Ages 63–95; Balanced; Lower Long-Term Return; 2.5% inflation |
Each conversion is modeled once at age 63. The fixed-conversion comparison uses age 64 as the first age with no conversion.
Modeled results
| Result | No conversion | $50,000 once | $100,000 once |
|---|---|---|---|
| Age-65 IRMAA tier | Base premium | Tier 2 | Tier 4 |
| Age-65 annual IRMAA surcharge above base premiums (future dollars) | $0 | $3,031 | $6,677 |
| Cumulative estimated taxes through 95 (annual future-dollar amounts) | $640,163 | $586,918 | $612,409 |
| Age-95 balance, inflation-adjusted | $898,547 | $893,599 | $790,635 |
The $50,000 conversion reduces cumulative modeled taxes but adds an estimated age-65 Medicare surcharge. The $100,000 conversion crosses more IRMAA tiers and produces the weakest ending balance in this projection. Under the default “avoid conversion-caused IRMAA increases” optimizer settings, No Conversion is recommended for this plan. That recommendation is only the strongest eligible policy tested under these assumptions.
What the example means
IRMAA is a cost of a conversion, not proof that the conversion is always wrong. A useful decision compares current conversion tax, later taxes and RMDs, after-tax balances, Medicare surcharges, spending coverage, and the value of Roth flexibility. Confirm the actual conversion-year MAGI and the official thresholds for the Medicare premium year, which is generally two years later. Future premium-year thresholds may not yet be published when the conversion decision is made.
Recreate the study
- Load the study inputs and compare the 67 · No Roth row with the $50,000 Fixed row.
- The loaded First Age With No Conversion is 64, so Fixed models one conversion at age 63.
- Inspect age 65 in Year-by-Year Details, then repeat with a $100,000 fixed conversion.
- Run the optimizer with the IRMAA guardrail enabled.
Related resources
See the two-year effect
Compare the conversion year with its later Medicare premium year.
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