Roth Conversion at 63: Worth It for a $1.2M 401(k)?

For a 63-year-old retired CPA holding a $1.2 million traditional 401(k), the Roth conversion question is less about whether it's a good idea and more about timing and tax arithmetic. With no earned income, your marginal rate is likely lower than it was during your working years—but that window closes once Required Minimum Distributions (RMDs) kick in at 73. Converting now lets you lock in today's rates on dollars that would otherwise be taxed later, potentially at higher effective rates once RMDs stack on top of Social Security and investment income.

The core trade-off is straightforward: you pay income tax on the converted amount now, in exchange for tax-free growth and withdrawals later. For a $1.2 million balance, a full conversion would be impractical—it would push you into the top brackets and trigger a massive tax bill. But partial conversions, targeting the space between your current taxable income and the top of the 24% or 28% bracket, can be highly efficient. A retired CPA likely already understands the math; the real question is whether the liquidity exists to pay the conversion tax from outside the retirement account, which preserves the full balance for compounding.

The RMD and Legacy Angle

RMDs at 73 will force distributions based on IRS life-expectancy tables, and for a $1.2 million account, those annual withdrawals will be sizable—likely pushing you into higher brackets than you occupy today, especially if you delay Social Security to 70. Roth conversions reduce future RMDs by shrinking the pretax balance, and they also eliminate the tax bomb for heirs, who under current rules must drain inherited IRAs within 10 years. If leaving a tax-free inheritance matters to you, conversions are a strategic tool; if you plan to spend down the account in retirement, the benefit is thinner.

One overlooked factor is the 5-year seasoning rule: converted funds must sit in the Roth for five years before earnings can be withdrawn tax-free, though contributions (the converted amount) are always accessible. At 63, you have ample runway before age 73, making now an ideal window. However, don't ignore the Net Investment Income Tax (3.8% on investment earnings above $200k for single filers) and the fact that conversions count as income for Medicare IRMAA surcharges two years later—a real cost that can erode the benefit.

Bottom line: a partial Roth conversion is likely worth doing, but only if you can pay the tax from cash reserves and you stay within your current bracket. Run a multi-year projection that models RMDs, Social Security claiming, and IRMAA thresholds. For a retired CPA, the numbers are the answer—and in most scenarios, converting 20-30% of the balance over the next five years beats doing nothing.