The Roth Conversion Strategy Affluent Investors Over 55 Are Using to Empty Their 401(k)s Before Required Distributions

The Bogleheads forum is full of posts that read the same way: a 56-year-old executive, $1.8 million in a traditional 401(k), a target retirement date of 60, and a creeping suspicion that the account has gotten too big. The instinct is to keep deferring. The math says otherwise, and the window to fix it is narrower than most people realize.

Affluent investors in this band have discovered something their advisors used to whisper about and now broadcast openly: the years between retirement and Social Security claiming are the cheapest tax real estate most Americans will ever own. Under SECURE 2.0, anyone born between 1951 and 1959 begins required minimum distributions at age 73, while those born in 1960 or later get to age 75. For our 56-year-old, that is a 17-year runway to drain the traditional account on their own terms.

Why Doing Nothing Is the Expensive Option

Start with the compounding problem. A $1.8 million balance growing at 6% net of fees reaches roughly $4.85 million by age 73. The IRS Uniform Lifetime Table divisor at 73 is 26.5, which makes the first mandatory withdrawal $183,000, every year, indexed up as the divisor shrinks. That income lands on top of Social Security, pension cash flow, and any taxable account dividends.

The result is the tax cascade. Ordinary income at that level pushes a married filer well past the 2% target inflation baseline that anchors bracket adjustments, drags 85% of Social Security into taxable income, and trips IRMAA. In 2026, IRMAA begins at $109,000 MAGI for single filers and $218,000 for joint filers, and the surcharges climb in five tiers from there. A single RMD year can manufacture an extra $4,000 to $9,000 in Medicare premiums two years later.

The 17-Year Drawdown Plan

The strategy is bracket filling. The 2026 schedule keeps the 22% bracket open up to $105,700 for single filers and $211,400 for joint filers, courtesy of inflation indexing under the One Big Beautiful Bill Act. Converting $80,000 per year for 17 years at the 22% bracket costs roughly $300,000 in conversion taxes, spread thin enough to never trigger the next bracket or IRMAA.

The cumulative effect is what makes this work. Total nominal conversions reach $1.36 million, splitting the account roughly 50/50 between traditional and Roth by age 73. First-year RMDs fall by about half. Wade Pfau’s research on conversion timing pegs the lifetime tax savings at approximately $400,000 for a household in this profile, because the alternative pulls every dollar out at 24% or higher once Social Security and pension income stack on top.

The Levers That Actually Move the Needle

Most retirees do not start converting until 65, which leaves only eight years before RMDs hit and forces conversions into higher brackets. Four execution details separate the savings from the regret:

1. IRMAA windowing. Keep MAGI under the $109,000 single / $218,000 joint threshold during every two-year lookback. If a conversion year pushes income past that line, Medicare premiums two years later carry a surcharge that erases part of the bracket-filling benefit.
2. Convert into drawdowns. When the market drops 15% or 20%, the same dollar conversion moves more shares into the Roth. Recovery happens tax-free inside the new account. With the 10-year Treasury near 5% and the Fed Funds rate near 4% after three cuts since October, valuation pullbacks become the cheapest conversion opportunities.
3. Pay the tax from a taxable account. Withholding the conversion tax from the IRA itself defeats the strategy by shrinking the tax-free compounding base. Cash from a brokerage settlement fund preserves the full conversion amount inside the Roth.
4. Use Roth as the inheritance vehicle. Under the SECURE Act 10-year rule, heirs must drain inherited retirement accounts within a decade. A Roth passes that obligation along tax-free; a traditional account hands beneficiaries a forced income spike during their peak earning years.

What to Do This Quarter

Pull the most recent IRS Uniform Lifetime Table and project the RMD on the current balance compounded to age 73. If the first-year withdrawal exceeds $150,000, the conversion math is almost certainly favorable. Build a 17-year conversion schedule that keeps each year’s taxable income under the next IRMAA tier, and pre-fund the tax bill in a taxable account so the IRA stays whole. If household income is layered with pension, deferred compensation, or large taxable dividends, the fee for a flat-rate CFP who specializes in conversions usually pays back inside the first year.