64-Year-Old With $1.1 Million 401(k) Drains It Early to Lock in 8% Guaranteed Social Security Bump

Linda is 64, retired last spring, and sitting on a $1.1 million traditional 401(k). Her Social Security statement projects a benefit of $5,181 per month at age 70. Instead of letting the 401(k) compound while claiming Social Security now, she is doing the opposite: pulling roughly $85,000 a year from the 401(k) while deferring Social Security for six more years. On paper it looks reckless. On a spreadsheet, it is one of the most tax-efficient strategies a retiree in her bracket can execute.

The 8% Guaranteed Return Nobody Else Can Match

Every year Linda delays claiming past her full retirement age, her benefit grows by 8%. That is a government-backed, inflation-linked increase stacked on top of the annual cost-of-living adjustment. The 2026 COLA came in at 2.8%, and because headline inflation has been running below that figure, the real purchasing power of a delayed benefit is compounding in Linda’s favor. The most current estimates for the 2027 COLA, from AARP and The Senior Citizens League, now cluster between 3.5% and 3.6%, up from 2026’s adjustment and the highest projected increase since 2023. The official figure will not be confirmed until mid-October, but even the lower end of that range reinforces the inflation-protection value of a larger delayed benefit.

Compare that 8% credit to what her portfolio can earn safely. The 10-year Treasury has been approaching 5%, trading near 4.96% as of mid-September 2026, up sharply from a year ago. The Federal Reserve held its target range at 3.5% to 3.75% at its July 29, 2026 meeting, but the September 16 decision arrives with J.P. Morgan Wealth Management and other strategists now expecting a 25 basis-point hike. A potential rate increase would lift short-term yields further, yet nothing on the risk-free side of Linda’s account statement pays 8% guaranteed. Delaying Social Security is functionally a bond ladder no broker sells.

The Bridge Math on $1.1 Million

Linda needs income now. The Bureau of Labor Statistics puts average annual household expenditures at $78,535 for 2024, and her budget is close to that. Six years of $85,000 withdrawals gross out to roughly $510,000, less than half the opening balance. If the remaining portfolio earns a blended 5% to 6% annually while she draws down, she will still have several hundred thousand dollars left when the $5,181 monthly check finally starts.

The tax angle is the piece most retirees miss. From 64 to 69, Linda has almost no other taxable income, so her 401(k) withdrawals fill up the standard deduction and the lower brackets before she ever touches the 22% rate. In 2026, a single filer’s 12% bracket ends at $50,400 of taxable income. Add the $16,100 standard deduction and Linda can bring in roughly $66,500 of gross traditional 401(k) income while staying entirely inside the 12% federal bracket. Stacking withdrawals on top of Social Security later would push those same dollars into a higher bracket, make 85% of her Social Security benefits taxable, and risk triggering her first IRMAA Medicare surcharge, which in 2026 kicks in at $109,000 of income for single filers.

The Roth Conversion Window Hiding Inside the Plan

The same low-income window that makes cheap withdrawals possible also opens a Roth conversion door. Linda can withdraw what she needs to live on, then convert an additional $30,000 to $40,000 into a Roth IRA each year while still staying under the 22% bracket. Every dollar converted before 70 is a dollar that will never appear in a future required minimum distribution calculation and never inflate the taxable portion of her benefit.

The window has grown more valuable in 2026. The One Big Beautiful Bill Act created a new $6,000 above-the-line bonus deduction for taxpayers age 65 and older, stacking on top of both the $16,100 standard deduction and the existing $2,050 age-65 additional deduction. The bonus is temporary, available for tax years 2025 through 2028, and it phases out above $75,000 of modified adjusted gross income for single filers, disappearing entirely at $175,000. For Linda, whose withdrawals and conversions will likely keep her well under that phase-out floor, the extra deduction means more room to withdraw or convert at low rates before hitting the 22% bracket. Every dollar of additional headroom is a dollar she can either spend at a low tax cost or shelter in a Roth permanently.

A fuller walkthrough of the timing lives inside The Social Security Decision. By the time RMDs begin at 75, her traditional balance is smaller, her Roth is meaningful, and her Social Security check is 24% larger than it would have been had she claimed at her full retirement age of 67.

Readers can model their own version with different balances and claiming ages:

The break-even point on delayed claiming typically lands in the early 80s. Anyone with reasonable health and family longevity clears it without difficulty.

What to Do Before Year-End

1. Pull your personalized Social Security statement. Confirm the exact benefit at 62, at full retirement age, and at 70. The 8% delayed credit only accrues between full retirement age and 70, not from 62 onward.
2. Map your withdrawals against the tax brackets. The 2026 12% bracket for single filers ends at $50,400 of taxable income. Add the $16,100 standard deduction plus the $2,050 age-65 additional deduction. If you are 65 or older and your MAGI is below $75,000, stack the new $6,000 OBBBA senior bonus deduction on top to find your gross income ceiling. Withdraw enough to fill that space, then decide whether a partial Roth conversion into the 22% bracket still beats the future tax cost of leaving the money in traditional. Keep in mind that the $6,000 senior bonus phases out above $75,000 MAGI and sunsets after the 2028 tax year.
3. Watch the two-year IRMAA lookback. Income in the calendar year you turn 63 sets your Medicare Part B and D premiums at 65. The 2026 first-tier surcharge threshold for single filers is $109,000. If a large withdrawal or conversion is coming, model the premium surcharge before you sign the paperwork.

Editor’s note: The 10-year Treasury yield figure has been updated to reflect current levels approaching 5% as of mid-September 2026, the 2027 Social Security COLA estimate has been revised to the current consensus range of 3.5% to 3.6% (per AARP and The Senior Citizens League), and context has been added noting that the Federal Reserve’s September 16, 2026 meeting arrives with major strategists now projecting a 25 basis-point rate hike.

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