Quick Read – A $1.6M 401(k) growing 7% annually reaches $4.4M by RMD age, pushing the first $166,000 withdrawal into a near-40% effective tax rate. – Converting $200,000 pre-tax to Roth at 32% costs $64,000 upfront but eliminates roughly $122,000 in future RMD taxes, netting…
8,000 in present-value savings. – Pay the conversion tax from outside taxable savings, not from the 401(k) balance itself. Using retirement funds to cover the bill erases most of the benefit. – A 58-year-old software executive earning $400,000 posted on a personal finance forum last month asking why her advisor kept pushing an “in-plan Roth conversion” on her $1.6 million traditional 401(k)
She already maxes contributions, already funds a backdoor Roth IRA, and is a decade from retirement. The advisor’s pitch: pay tax now at her current marginal rate to eliminate a specific future problem. The math worked out to roughly $58,000 in taxes she would never have to pay on required minimum distributions.
That number comes from the interaction of three rules that most high earners underestimate. Why the RMD Cliff Hits Highest Earners Hardest Traditional 401(k) balances grow tax-deferred, and every dollar comes out as ordinary income after age 73. On a $1.6 million balance growing at 7% for 15 years, the account reaches roughly $4.4 million by RMD age.