Anyone Holding Over $700,000 in a Traditional 401(k) Is Being Warned: the First RMD Can Push 85 Percent of Social Security Onto the Tax Return
Retirees holding substantial balances in traditional 401(k) accounts are facing a significant tax warning as they approach their mid-seventies. For a single individual with $700,000 in such an account, the arrival of the first required minimum distribution (RMD) could result in 85 percent of their Social Security benefits becoming subject to federal income tax. This scenario specifically impacts those who will reach age 75 in 2035, a group that includes current 66-year-olds born in 1960 or later.
Secure 2.0 and the RMD AGE
Under the SECURE 2.0 federal retirement legislation enacted in 2022, the age at which RMDs must begin is set at 75 for this demographic. Using projected 2026 tax regulations as a baseline, financial experts illustrate how a $25,000 annual pension combined with $36,000 in Social Security benefits creates a complex tax situation. The Internal Revenue Service determines the taxability of benefits using a metric called combined income, which is the sum of a taxpayer's adjusted gross income and half of their Social Security payments.
For single filers, these benefits begin to face taxation once combined income exceeds $25,000. When that figure passes $34,000, every additional dollar of income can cause 85 cents of Social Security to become taxable, up to a maximum of 85 percent of the total benefit. Because these specific thresholds are written into the tax code and are not adjusted for inflation, standard cost-of-living increases and pension raises continually push more retirees into higher tax brackets.
THE TAX Torpedo Effect
In the case of the hypothetical retiree, their combined income sits at $43,000 before taking any 401(k) withdrawals. This amount already surpasses the upper limit, making approximately $12,150 of their Social Security taxable. However, the first RMD significantly changes the math. By dividing the $700,000 account balance by the age-75 distribution factor of 24.6, the retiree must withdraw roughly $28,455.
This mandatory withdrawal pushes the total combined income to approximately $71,455. Consequently, the taxable portion of Social Security hits the 85 percent ceiling, or $30,600. While the actual withdrawal is $28,455, it triggers the taxation of an additional $18,450 in benefits. The result is a total of $46,905 in new taxable income appearing on the tax return from a single distribution.
Medicare Premiums and Irmaa Thresholds
This phenomenon, often called the tax torpedo, is most damaging when combined income falls between $43,000 and $64,706. In this range, every dollar taken from a 401(k) adds $1.85 to the total taxable income. This can effectively spike a 12 percent tax rate to 22 percent, or a 22 percent rate to roughly 41 percent.
Beyond income taxes, retirees face risks regarding Medicare costs. With the RMD included, this retiree’s modified adjusted gross income reaches $84,055. Under 2026 guidelines, this remains $24,945 below the $109,000 threshold for the Income-Related Monthly Adjustment Amount (IRMAA). If a retiree exceeds that mark due to a larger balance or an unexpected capital gain, their monthly Part B premiums could jump from $202.90 to $284.10, usually starting two years after the income spike.
Source: 247wallst.com · 2026-11-01