Financial Basics · Tax Concepts

Roth Conversion

Definition

A Roth conversion moves money from a traditional IRA or 401(k) to a Roth IRA. You pay ordinary income tax on the converted amount in the year of conversion; the money then grows tax-free and is never subject to RMDs.

Why it matters in retirement

The best time to convert is usually in the low-income window between retiring and starting RMDs at 73 — but the math is specific to your brackets, tax rates, IRMAA tiers, and expected return. Done right, conversions can save six figures in lifetime taxes.

Key Numbers — 2026

Optimal window (typical)
Age 63–72
5-yr rule per conversion
5 yrs
IRMAA tier 1 (MFJ 2026)
$212,000 MAGI
No income limit
Anyone can convert

Pros

  • Tax-free future growth
  • No RMDs on Roth
  • Tax-free inheritance for heirs
  • Hedge against future tax increases

Cons

  • Large upfront tax bill
  • Can trigger IRMAA 2 years later
  • Can make Social Security more taxable
  • 5-year rule on each conversion

Common mistakes

  • Converting without a plan for paying the tax
  • Ignoring IRMAA (you see the bill 2 years later)
  • Converting in years with ACA subsidies (losing them costs more than the tax saves)
  • Converting all at once instead of filling brackets annually

Related

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