The Inherited 401(k) Mistake That Quietly Cost a $750,000 Beneficiary $120,000 in Excess Taxes

"Before 2020, a non-spouse beneficiary could stretch distributions across her own lifetime, dragging out the tax bill for decades. The SECURE Act ended that for most heirs. Under the 2024 IRS final regulations, a non-eligible designated beneficiary must empty an inherited 401(k) by December 31 of the tenth year after the original owner's death."

"Here is the part most beneficiaries miss. Because her father died after his required beginning date, she also owes annual RMDs in years 1 through 9, calculated against her own single life expectancy. The 10-year rule sets the deadline. The annual RMD requirement sets the floor. Skipping a required distribution triggers a 25% excise tax on the missed amount, reducible to 10% if corrected promptly."

"Run the numbers on her stated plan. She defers meaningful withdrawals, the account compounds at roughly 5% (a reasonable assumption with the 10-year Treasury near 4.4%), and by year 10 the balance reaches roughly $1.04 million. Stack that on top of her $250,000 salary in the year she pulls it, and the inherited dollars land squarely in the 35% and 37% federal brackets. The federal bill alone runs about $370,000."

"Now run the disciplined version. She withdraws roughly $75,000 a year for ten years, leaving a small growth tail for the final distribution. Each slice piles onto her $250,000 salary and tops out in the 32% bracket. Lifetime federal tax: approximately $250,000. The gap between the two paths is roughly $120,000 in cash that goes to the Treasury instead of"

A non-spouse beneficiary of an inherited 401(k) generally must empty the account by December 31 of the tenth year after the original owner’s death under SECURE Act rules. When the original owner died after the required beginning date, the beneficiary must also take annual required minimum distributions in years 1 through 9 based on the beneficiary’s own life expectancy. Missing a required distribution triggers a 25% excise tax on the missed amount, reduced to 10% if corrected quickly. A delayed withdrawal plan can compound the balance to about $1.04 million by year 10, pushing withdrawals into higher federal brackets and creating a large tax bill. A disciplined approach withdrawing about $75,000 annually for ten years can keep withdrawals in lower brackets and reduce total federal taxes by roughly $120,000.

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