Roth Conversion Bracket Fill 2026 Calculator
Roth conversions in low-income years (pre-Social Security, pre-RMDs) are one of retirement planning's highest-ROI moves. Convert just enough to 'fill' your current tax bracket without spilling into the next. Strategic multi-year conversion at 22-24% can save 30-50% vs RMD-forced distributions at 32-37% later.
Why Bracket Fill Works
Marginal brackets jump significantly: 22% to 24% (small jump), 24% to 32% (big jump). Filling exactly to top of current bracket maximizes Roth conversion at current marginal rate without spilling into next. Example: $30K income room before 32% bracket — convert $30K at 24%, save 8% vs converting $30K at 32% next year.
IRMAA Awareness
Medicare IRMAA brackets create cliffs at $106K/$133K/$167K/$200K MAGI single. Cross by $1, owe $1,000+ extra Medicare premium for year. Roth conversion that pushes MAGI over IRMAA threshold often costs more in Medicare than tax savings. Always model IRMAA impact before converting. Sweet spot: convert up to $5K below next IRMAA threshold.
The Best Conversion Window
Age 60-72 is ideal: post-retirement (low W-2 income), pre-Social Security (no SS in AGI), pre-RMDs (no forced distribution). Each year converted lowers future RMDs proportionally. SECURE 2.0 raised RMD age to 73 (was 72) — extra year of conversion runway. Some convert to age 65 then pause for Medicare planning, restart at 67-72.
Source: IRC §408A (Roth IRA), §401(a)(9) (RMD), SECURE Act 2.0 §107 (RMD age), 2026 IRS bracket tables. Last updated: May 2026.