Decades of retirement saving build on steady paycheck contributions, employer matches, and the power of compounding.
But Vanguard’s latest research suggests the number you end up with may not be what ultimately determines whether your retirement plan succeeds.
The firm released Principles for Retirement Income on June 2, 2026, a detailed paper built around a finding that challenges how most people evaluate retirement readiness.
The research maps out strategies for tax efficiency, spending flexibility, and guaranteed income that could reshape how retirees draw down their savings.
Vanguard identifies the number that controls retirement success
The percentage of your savings you withdraw each year is the single most important variable in retirement planning, the Vanguard research concluded.
Vanguard found that annual withdrawals of 3.5% to 4%, after accounting for Social Security and other guaranteed income, can support a 30-year retirement. The calculation assumes pensions, annuities, and other reliable income sources are factored in first.
What makes the withdrawal rate so consequential is how sensitive portfolio longevity becomes to even minor adjustments in the percentage you draw each year.
Without a clear understanding of what their retirement savings can support, people often either limit spending out of fear they’ll run out of money or overspend in ways that threaten their long-term financial security and lifestyle.
A retiree holding $500,000 who reduces the withdrawal rate by half a percentage point can extend portfolio life by roughly five years, Vanguard calculated.
At a 5% rate, the money lasts about 29 years, while shifting to 4.5% stretches it to about 34 years under the firm’s assumptions.
Roth conversions could save retirees thousands on taxes
More than 80% of clients in Vanguard’s Tax-Efficient Retirement Strategy stand to benefit from Roth conversions when they are integrated into a broader retirement income strategy, the paper noted.
A Roth conversion shifts pre-tax dollars from a traditional IRA or 401(k) into a Roth for tax-free growth and withdrawals.
The years between retirement and the start of required minimum distributions, which begin at age 73 for those born between 1951 and 1959 and age 75 for those born in 1960 or later, often represent the lowest-income period of retirement.
More Retirement:
- Bank of America spotlights 401(k) tips you overlook
- Tennessee tax perks retirees should know
- Key social security updates you need to know for the rest of 2026
Converting during those lower-income years lets retirees lock in reduced rates and shrink the size of future required distributions, the paper noted. For married couples, conversions can also shield a surviving spouse from the steeper tax brackets that apply to single filers.
The research recommends withdrawing from taxable accounts first, followed by tax-deferred accounts, while preserving Roth savings for last.
In one model, this strategy cut lifetime taxes by roughly 14% by age 100 compared with withdrawing proportionally across all accounts.
Roth conversions during low-income retirement years could reduce lifetime taxes by 14% and shrink future required distributions.
How flexible spending and delayed retirement stretch your portfolio
The research highlights dynamic spending, a strategy that adjusts retirement withdrawals based on portfolio performance from the previous year. Retirees can spend slightly more after strong years and scale back during weaker periods to protect long-term savings.
Vanguard recommends limiting annual spending increases to 5% during strong market periods and capping reductions at 2.5% when portfolios decline.
The approach allows retirees to benefit from gains while reducing the chances of painful spending cuts later in retirement.
The firm also indicated that delaying retirement by one year could increase spending power by roughly 15% for a hypothetical investor earning $160,000.
Delaying Social Security beyond full retirement age can also raise monthly benefits by about 8% each year, according to Social Security Administration data.
Jason Fichtner, a former acting deputy commissioner and chief economist at the Social Security Administration, told CNBC that one way to think about it is that “claiming at any age before age 70 is a penalty.”
Vanguard’s cash buffer strategy and the cost of holding too much
The paper recommends maintaining a spending fund equal to about 12 months of planned portfolio withdrawals in a high-yield savings account or money market vehicle.
This cash buffer gives retirees access to funds daily without selling investments during market declines.
Holding too much cash, however, can create “cash drag,” where low-yielding reserves erode overall portfolio growth over time. Vanguard found that retirees holding three years of expenses in cash ended up with lower projected wealth than those holding one year.
Essentials, including housing, transportation, health care, food, and clothing and personal care, make up about 85% of total annual spending for early retirees aged 65 to 69, Vanguard’s analysis of RAND Health and Retirement Study data showed.
Covering those essentials with guaranteed income like Social Security or an annuity gives retirees a predictable floor for monthly expenses, the paper noted.
That layered structure pairs the cash buffer with steady income sources, reducing the need to sell investments at a loss during market downturns.
Joel Dickson, global head of advised strategies at Vanguard, said the research is designed to bring “clarity and discipline to retirement income” and the spending decisions it supports.