Roth Conversion Ladder Calculator 2026 — Multi-Year Bracket-Filler

A multi-year sequence of Roth conversions sized to fill a specific federal bracket (12%, 22%, or 24%) without pushing into the next one. The typical ladder runs from retirement age (around 60) to the year before RMDs begin (age 73 under SECURE 2.0, or 75 if born after 1960), drip-converting traditional IRA / 401(k) balances at the lowest sustainable blended tax rate. The result: a lower lifetime tax bill and smaller RMDs when you reach 73/75.

Our existing /roth-conversion-tax/ tool answers "how much tax do I owe if I convert $50K this year?" — a one-shot calculation with state taxes for all 50 states. This ladder calculator answers a different question: "across a multi-year window, how much should I convert each year to fill bracket X, what is the per-year bracket fill %, IRMAA tier, and 5-year access date?" Both tools are useful at different stages of planning.

For high-balance traditional accounts, you simply cannot fit the whole balance into the 12% bracket across a 10–15 year ladder — some money will remain and be taxed at higher RMD-era rates. Filling 22% or 24% trades a slightly higher conversion rate today for clearing the entire balance and avoiding 32%+ RMDs later. The right ceiling depends on your starting balance, ladder length, and expected RMD-era bracket.

IRMAA (Income-Related Monthly Adjustment Amount) is the Medicare Part B and Part D premium surcharge that kicks in above six MAGI thresholds. Crossing a tier by even $1 raises the surcharge for an entire year — a true cliff, not a phase-in. Because IRMAA looks back 2 years, a conversion in 2026 affects 2028 Medicare premiums. The calculator can cap conversions to keep MAGI below the next tier when relevant.

Each Roth conversion has its own 5-year clock for penalty-free access to the converted principal. The clock starts on January 1 of the conversion year, regardless of conversion date within the year. Withdraw converted principal before 5 years (and before age 59½) and you owe a 10% penalty on the conversion. The income tax was paid at conversion, so it is not re-taxed — only the 10% penalty applies. Once you hit 59½, the per-conversion rule drops away.

This calculator is federal-only. State conversion treatment varies widely: nine states have no income tax (FL, TX, NV, etc.), some exempt retirement income (IL, PA), some tax it fully, and a few (e.g. NY) offer a partial exclusion. For state-by-state numbers on a single conversion year, use our /roth-conversion-tax/ tool. For multi-year ladders, the federal blended rate is the dominant figure; expect state tax to add 0–9% on top depending on residency.

Pay from outside cash whenever possible. If you withhold tax from the conversion itself, that withheld amount is treated as a withdrawal — penalty-free only if you are 59½+ — and reduces the amount that grows tax-free in Roth. This calculator assumes outside-cash payment, so the full conversion lands in Roth. If you must pay from the IRA, expect the after-tax Roth balance to be roughly 20–30% lower than the figures shown.

A conversion adds to provisional income, which can push more of your Social Security benefits into the 50% or 85% taxable zone — effectively raising the marginal cost of the conversion above the headline bracket. The calculator treats taxable Social Security as part of "other taxable income" already at the user-supplied amount, but the conversion may push additional SS into taxability that is not modeled here. For users with significant SS benefits, the true marginal rate on conversions can be 1.5–1.85× the headline bracket — confirm with a tax pro before executing.