A single filer whose 2026 modified adjusted gross income is $90,000 can convert $19,000 to Roth before crossing the first IRMAA threshold at $109,000. Married filing jointly at $180,000, the room is $38,000 up to $218,000. IRMAA is a cliff, not a ramp: one dollar past the threshold adds $1,148 per person for the entire year.
Conversion room to the next IRMAA threshold (2026)
| Filing status | MAGI before converting | Next IRMAA threshold | Conversion room | Cost per person if you cross |
|---|---|---|---|---|
| Single | $70,000 | $109,000 | $39,000 | $1,148 |
| Single | $90,000 | $109,000 | $19,000 | $1,148 |
| Married filing jointly | $150,000 | $218,000 | $68,000 | $1,148 |
| Married filing jointly | $180,000 | $218,000 | $38,000 | $1,148 |
MAGI exactly on a threshold stays in the lower tier — the surcharge applies only above it — so the room shown is the full distance to the threshold. Medicare reads the return from two years earlier, so a conversion made in 2026 sets the premium for 2028. On a joint return each spouse enrolled in Medicare pays the surcharge, doubling the figure in the last column.
Methodology
Room computed with headroomToNextTier() and the dollar cost with annualSurcharge(), both from QuantCalc's parity-tested IRMAA module reading the 2026 CMS tier table (IRMAA_TIERS). See the 2026 IRMAA bracket dataset and the IRMAA cliff study.
Every figure on this page is computed at build time from QuantCalc's parity-tested calculation modules or a committed dataset — never hand-entered. Reference for research and planning only; not tax, legal, or investment advice.
Model this for your own numbers
The free QuantCalc calculator runs your actual balances, income, and filing status through the same parity-tested engine.
Open the free calculator →Planning conversions across several years? See the Roth Conversion Planner.
Changelog
- v2026.1 — first publication. Figures computed from the 2026 tax-constants mirror and committed datasets.
Cite this dataset
QuantCalc Research (2026). How much can I convert to Roth without triggering IRMAA in 2026?. https://quantcalc.app/answers/how-much-roth-conversion-before-irmaa/ (accessed <date>).
BibTeX
@misc{quantcalc2026howmuchcaniconverttorothwithouttriggerin,
title = {How much can I convert to Roth without triggering IRMAA in 2026?},
author = {{QuantCalc Research}},
year = {2026},
url = {https://quantcalc.app/answers/how-much-roth-conversion-before-irmaa/},
note = {Accessed <date>}
}Machine-readable citation metadata (schema.org identifier and citation fields) is embedded in this page's JSON-LD, at the stable identifier https://quantcalc.app/answers/how-much-roth-conversion-before-irmaa/.