A Couple With a $1 Million 401(k) Can Keep Social Security Tax-Free. The Income Mix Matters More Than the Withdrawal Order
Most retirees assume a seven-figure 401(k) and Social Security simply cannot coexist without a tax bill, but the income sources a household draws from each year can change everything about that outcome.
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A seven-figure traditional 401(k) can sit alongside fully tax-free Social Security if the household controls what shows up on the tax return each year. Consider a hypothetical married couple filing jointly with a $1 million traditional 401(k), no required withdrawals yet, and $50,000 in annual Social Security.
This year they withdraw $7,000 from the pretax 401(k) and draw $33,000 from an existing qualified Roth account. With no other income, that gives them $90,000 of gross cash flow. They owe no federal tax on their Social Security.
The outcome depends on the kind of dollars each account produces, and the order in which the accounts are drawn from matters much less. The plan also needs something many seven-figure savers lack: a separate qualified Roth account big enough to cover most of the spending.
How a $32,000 Base Amount Decides Whether Benefits Get Taxed
IRS Publication 915, the agency’s guide to taxing Social Security, uses a simple test. Add one-half of your benefits to all your other income, then compare the total with a base amount for your filing status. According to IRS Publication 17, the agency’s general guide to individual income tax, that base amount is $32,000 for married couples filing jointly.
This couple’s combined income comes to exactly $32,000: the $7,000 taxable withdrawal plus half of the $50,000 in benefits. The total does not exceed the base amount, so none of their benefits is included in federal taxable income.
The Roth draw never enters the test. Publication 17 says qualified Roth distributions are excluded from gross income. That keeps the entire $33,000 Roth withdrawal out of the Social Security formula.
This result is different from a more common one. Many retirees have part of their benefits included in income, and then the standard deduction wipes out the tax, but those benefits are still taxable on paper and still stack on top of any new income. Here, the benefits stay out of taxable income from the start.
Small Income Streams That Quietly Break the Plan
Because the couple is right at the base amount, every extra dollar of countable income matters, and bank interest, dividends and capital gains from a taxable brokerage account all count. So does municipal bond interest: IRS Publication 915 tells taxpayers to include tax-exempt interest in the comparison, even though that interest escapes regular income tax.
Roth conversions raise income too. According to IRS Publication 590-A, the agency’s guide to IRA contributions and conversions, converted amounts are included in gross income for the year of the conversion. A conversion in a year when benefits are being paid would push this couple over the line.
The $1 million balance does not trigger anything by itself. Required minimum distributions (RMDs) can. The IRS generally calculates those withdrawals by dividing the previous year-end balance by the factor for the retiree’s age in its Uniform Lifetime Table. Once they begin, the couple may have to withdraw far more than $7,000, even if they don’t need the money.
Build the Roth Reserve Before Benefits Start
The gap between retiring and claiming Social Security is the clearest window for building this flexibility. Converting traditional dollars to Roth costs tax up front. But no benefits are being paid yet, so the conversion income has nothing to drag into the base-amount test. Each converted dollar can later pay for spending that the Social Security test ignores.
That window closes over time. As referenced, IRS Publication 590-A notes that amounts required to be distributed as RMDs for a given year cannot be converted. Once RMDs begin, part of each year’s withdrawal is no longer available to convert.
An ordinary rollover from a traditional 401(k) to a traditional IRA does nothing for this goal. Withdrawals from the IRA remain fully taxable and still count toward the base-amount test. Only Roth dollars, or money that has already been taxed, create spending power outside the formula.
Rerun the Income Mix Every Year
This setup only works while the inputs hold steady. Cost-of-living adjustments (COLAs) raise benefits, interest income changes with rates, and the Roth reserve shrinks with every withdrawal. The base amount itself has no inflation adjustment written into the law. Recalculate combined income each January from actual statements, and leave a buffer below the base amount instead of aiming for the edge.
Next, map out when each spouse’s required withdrawals begin and how large they could be. Then compare the cost of converting now with the future taxes it could avoid. A bigger Roth reserve can help keep benefits tax-free, but the household’s full income picture decides the result.
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Gerelyn Terzo is the author of dividend investing handbook "Dividend Investing Strategies: How to Have Your Cake & Eat It Too." A veteran financial journalist, she covers agri-finance for outlets like Global AgInvesting and the broader stock market and personal finance for 24/7 Wall Street. She began at CNBC and later helped launch Fox Business in New York. Gerelyn currently resides in Woodland Park, Colorado and dabbles in nature photography as a hobby.
