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 grown dangerously large. The instinct is to keep deferring. The math says otherwise, and the window to act is narrower than most people realize.

Affluent investors in this situation have discovered something their advisors used to whisper about and now broadcast openly: the years between retirement and Social Security claiming offer the most favorable tax environment most Americans will ever see. Under SECURE 2.0, anyone born between 1951 and 1959 begins required minimum distributions at age 73, while those born in 1960 or later face mandatory withdrawals only at age 75. For a 56-year-old in either cohort, that translates to a 17-to-19-year runway to drain the traditional account on their own terms rather than the IRS’s.

Why Doing Nothing Is the Expensive Option

The core problem is compounding inside a tax-deferred account. 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 age 73 is 26.5, which puts the first mandatory withdrawal at approximately $183,000. That income arrives every year, indexed higher as the divisor shrinks, and stacks on top of Social Security, any pension cash flow, and taxable account dividends.

The result is what planners call the tax cascade. Ordinary income at that level pushes a married filer well past the threshold that anchors bracket adjustments, pulls 85% of Social Security into taxable income, and triggers IRMAA. In 2026, IRMAA begins at $109,000 in modified adjusted gross income for single filers and $218,000 for joint filers, then climbs through five surcharge tiers. The first tier alone adds roughly $1,148 per year to Medicare costs. The surcharge is calculated on the tax return filed two years prior, meaning a single high-RMD year can silently generate an extra $4,000 to $9,000 in Medicare premiums two years later. The IRMAA cliff is unforgiving: crossing a tier by one dollar triggers the full surcharge for that entire tier, and the bill arrives with no warning.

The 17-Year Drawdown Plan

The strategy is bracket filling: converting just enough each year to stay inside a favorable rate band, repeated over a long runway. 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, signed into law in July 2025, which permanently locked in the seven-bracket structure. Converting $80,000 per year for 17 years at the 22% rate costs roughly $300,000 in conversion taxes, spread thin enough to stay clear of the next bracket and below every IRMAA tier.

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

One additional lever deserves attention. The One Big Beautiful Bill Act introduced a temporary $6,000 senior bonus deduction per person for taxpayers aged 65 and older, available for tax years 2025 through 2028. The deduction phases out for single filers with modified adjusted gross income above $75,000 and for joint filers above $150,000, disappearing entirely for single filers above $175,000 and joint filers above $250,000 (assuming one qualifying spouse). When both spouses are 65 or older, the combined $12,000 deduction phases out fully at $350,000 in joint MAGI. For retirees who retire early and keep conversions modest in their first years post-65, the deduction effectively widens the low-bracket window, making those earliest conversion years especially productive.

The Levers That Actually Move the Needle

Most retirees do not start converting until 65, leaving only eight years before RMDs force withdrawals into higher brackets. Four execution details separate the tax savings from the regret:

1. IRMAA windowing. Keep modified adjusted gross income under the $109,000 single / $218,000 joint threshold during every two-year lookback period. 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. Crossing a threshold by a single dollar triggers the full surcharge for that entire tier, with no prorated relief.
2. Convert during drawdowns. When the market drops 15% or 20%, the same dollar amount converts more shares into the Roth, and recovery then happens tax-free inside the new account. The 10-year Treasury yield reached 5.36% on October 7, 2026, a 24-year high, before settling back to approximately 5.24% by October 9. The Federal Open Market Committee delivered its first rate hike since 2023 at its September 16 meeting, raising the federal funds rate by a quarter point to a target range of 3.75% to 4.00% under Chair Kevin Warsh. Markets now price roughly an 86% probability of an additional 25-basis-point hike before year-end. A tightening cycle that pushes valuations lower creates a wider window for cost-efficient conversions.
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 converted 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 forces beneficiaries into a compressed income spike during their own peak earning years, concentrating all that deferred tax into the worst possible bracket environment.

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. A first-year withdrawal exceeding $150,000 is a strong signal that the conversion math is favorable. Build a multi-year conversion schedule that keeps each year’s taxable income below the next IRMAA tier, and pre-fund the tax bill in a taxable account so the IRA stays whole.

For retirees turning 65 between 2025 and 2028, model the senior bonus deduction to find the years where the effective bracket cost of a conversion is lowest, keeping the full phase-out thresholds in view. If household income layers in pension payments, deferred compensation, or large taxable dividends, the fee for a flat-rate CFP who specializes in conversions typically pays back inside the first year. With Treasury yields pushing 24-year highs and the Fed signaling at least one more rate increase before 2026 ends, the cost of waiting grows on two fronts: a larger taxable account and a less favorable valuation backdrop for conversion timing.

Editor’s note: This update reflects the FOMC’s September 16, 2026 decision to raise the federal funds rate by 25 basis points to a target range of 3.75% to 4.00%, the first hike since 2023, and refreshes the 10-year Treasury yield to approximately 5.24% as of October 9, 2026, after the benchmark briefly touched 5.36% on October 7, a 24-year high. The market-implied probability of a further December hike has been updated to roughly 86% based on CME FedWatch data.

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