The Hidden 401(k) Tax Bomb That Hits a $1.3 Million Saver With $19,800 in Their First RMD Year

A 73-year-old retiree with a $1.3 million traditional 401(k) and $36,000 in Social Security faces required minimum distributions starting in 2026. Using the IRS Uniform Lifetime Table divisor of 26.5, the first-year RMD is $49,057, and failing to withdraw the required amount triggers a 25% excise tax on the shortfall. The RMD increases provisional income so that 85% of Social Security becomes taxable, adding about $30,000 to adjusted gross income. Total ordinary income reaches roughly $85,000. Standard and senior deductions reduce taxable income to about $61,000, but federal taxes still total around $8,335, with additional state income tax likely adding several percentage points.

"At age 73, the IRS Uniform Lifetime Table uses a divisor of 26.5. A $1.3 million balance divided by that figure produces a mandatory withdrawal of $49,057. That number is non-negotiable, and missing it triggers a 25% excise tax on the shortfall."

"Layered on top, the RMD pushes provisional income high enough that 85% of the $36,000 Social Security benefit becomes taxable, adding roughly $30,000 to adjusted gross income. Total ordinary income lands near $85,000."

"A single 65-plus filer in 2026 gets the standard deduction of $16,100, plus the senior add-on of $2,050, plus the new $6,000 senior bonus deduction available in full while MAGI stays under $75,000 single. Stack those together and the retiree shelters $24,150 of income, leaving taxable income near $61,000."

"The federal bill stacks across three brackets: 10% on the first $11,925 equals $1,193, 12% on the next $36,550 equals $4,386, and 22% on the remaining $12,525 equals $2,756. Total federal liability comes in around $8,335."

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