Retirement planning has long revolved around the “4% rule,” the idea that new retirees can safely withdraw 4% of their portfolio in the first year and adjust that dollar amount for inflation thereafter. Now William Bengen, the financial planner who originally popularized that benchmark, says his latest research supports a higher starting rate of about 4.7%, but only for investors who understand the tradeoffs and limits behind that number. Before anyone upgrades their paycheck from their portfolio, I think it is crucial to unpack what Bengen is really saying, how it differs from the classic rule, and why the margin for error may be thinner than it looks.
How Bengen moved from 4% to about 4.7%
Bengen’s original work in the 1990s examined historical U.S. market returns and asked a simple question: what initial withdrawal rate would have survived every 30‑year retirement period in the data set, assuming a mix of stocks and bonds and annual inflation adjustments? That research produced the now‑famous 4% guideline, which became a cornerstone of retirement advice. In more recent analysis, he revisited the same core question with a longer history of data, more asset classes, and refined assumptions, and he concluded that a retiree who follows his updated framework could have started closer to 4.7% while still surviving the worst historical sequences of returns, according to his latest safe withdrawal research.
The jump from 4% to roughly 4.7% is not a casual tweak, it reflects a more granular look at how different stock segments and bond mixes behaved in past downturns and recoveries. Bengen’s expanded data set includes additional decades of returns and a more detailed breakdown of U.S. equities, which allowed him to test portfolios that tilt toward certain styles rather than just a broad market index. His conclusion is that, under specific conditions, a retiree could have withdrawn about 4.7% in year one and still made it through the worst 30‑year stretches on record, a finding that has been widely cited in recent coverage of his updated rule. That higher figure, however, is not a blanket permission slip, it is a best‑case ceiling built on very particular assumptions.
The original 4% rule and what it actually promised
Before anyone upgrades their withdrawal rate, it helps to remember what the original 4% rule did and did not guarantee. Bengen’s first studies were designed to find a rate that would have survived every 30‑year retirement window in the historical record, even the worst ones, for a portfolio that held a diversified mix of large‑cap U.S. stocks and intermediate‑term government bonds. The 4% figure was never meant as an average or a guess, it was a floor that would have worked even for someone unlucky enough to retire into a period like the mid‑1960s, when high inflation and weak real returns punished both stocks and bonds, as his early withdrawal‑rate paper shows.
That original framework also assumed a very specific pattern of behavior: the retiree withdraws 4% of the initial portfolio value in year one, then simply increases that dollar amount with inflation every year, regardless of what markets do. There was no dynamic spending, no tactical shifts in response to valuations, and no attempt to time the market. The promise was stark and simple, if you follow those rules and markets behave as they did in the historical data, you would not have run out of money over 30 years. Later researchers, including teams that revisited the rule using different return assumptions and international data, have confirmed that the 4% benchmark is conservative but still sensitive to sequence‑of‑returns risk, as summarized in several modern analyses of safe withdrawal rates.
Why the new 4.7% figure depends on portfolio design
The most important caveat behind Bengen’s higher number is that it assumes a very specific portfolio, not just any generic 60/40 mix. In his updated work, he finds that adding a meaningful allocation to small‑cap value stocks, alongside large‑cap equities and intermediate‑term bonds, historically boosted returns enough to support a higher initial withdrawal rate without increasing failure rates over 30‑year periods. The logic is straightforward: small‑cap value has delivered higher long‑term returns in U.S. data, and when combined with other asset classes it improved the portfolio’s resilience in bad sequences, which is why his 4.7% estimate is tied to a particular blend that includes a dedicated slice of small‑cap value exposure.
That nuance matters for real‑world investors who may hold broad index funds like Vanguard Total Stock Market or an S&P 500 ETF without any explicit tilt toward small‑cap value. If your portfolio does not resemble the mix Bengen modeled, then the historical support for 4.7% is weaker, because the backtests that produced that figure relied on the higher expected returns and diversification benefits of those specific segments. Other researchers who have tested withdrawal rates using more conventional index portfolios often land closer to 3.8% to 4.2% as a sustainable starting point, depending on bond yields and valuation assumptions, as reflected in recent safe‑rate estimates. In other words, the extra 0.7 percentage point is not free, it is the payoff for accepting a more specialized equity allocation that may not match every investor’s risk tolerance.
Time horizon: 30 years is not everyone’s retirement
Another key assumption behind both the 4% and 4.7% figures is the length of retirement. Bengen’s work focuses on 30‑year periods, which is a reasonable planning horizon for someone retiring in their mid‑60s, but it may be too short for people who stop working earlier or who want to plan for a longer potential lifespan. If you expect your money to last 35 or 40 years, the safe initial withdrawal rate that would have survived every historical period drops, because the portfolio has to endure more market cycles and more years of inflation compounding against it, a pattern that shows up clearly in extended‑horizon withdrawal‑rate simulations.
Conversely, some retirees have shorter horizons, either because they retire later or because they are planning around other sources of guaranteed income such as pensions or annuities that kick in after a decade or two. For them, a 30‑year worst‑case lens may be overly conservative, and a higher starting rate could be reasonable if the spending plan is explicitly time‑limited. Several analyses that model different horizons show that safe withdrawal rates can rise meaningfully when the target period shrinks to 20 or 25 years, as summarized in recent retirement‑horizon studies. The point is that Bengen’s 4.7% is calibrated to a specific 30‑year frame, and stretching or compressing that frame changes the math in ways that investors need to acknowledge before adopting any single number.
Market valuations, bond yields, and today’s starting point
Historical backtests are powerful, but they are backward looking, and the conditions that supported a 4.7% rate in the past may not match the environment new retirees face today. Safe withdrawal research is highly sensitive to starting valuations and bond yields, because those factors shape the returns a portfolio is likely to earn in the first decade of retirement, when sequence risk is most acute. When stock valuations are elevated and bond yields are low, forward‑looking models tend to project lower real returns, which in turn pull down the sustainable initial withdrawal rate, a pattern highlighted in several valuation‑aware analyses of retirement income.
Recent work that blends historical data with current yield and valuation metrics often lands on a more cautious range, with some researchers suggesting that new retirees might want to start closer to 3.3% to 3.8% if they want a very high probability of success over 30 years. Those figures are not direct contradictions of Bengen’s 4.7% ceiling, they are different answers to a slightly different question: what is safe given today’s starting conditions rather than the full sweep of history. Bengen himself has acknowledged in interviews that his higher rate is a historical maximum under specific assumptions, not a universal recommendation for every retiree in every market, a nuance that is echoed in recent interviews about his updated rule.
Inflation shocks and sequence‑of‑returns risk
One of the main reasons Bengen’s original 4% rule was so conservative is that it had to survive periods of high inflation and poor real returns, not just average conditions. The worst historical retirements in his data set were those that began just before inflation spikes or long stretches of weak markets, when the combination of rising living costs and falling portfolio values created a dangerous squeeze. His updated 4.7% figure still has to pass those same stress tests, but it does so with a portfolio that is more heavily exposed to equities, which means the path of returns in the first decade becomes even more critical, as shown in his sequence‑risk analysis.
Recent inflation episodes have reminded retirees how quickly purchasing power can erode when prices jump faster than expected. A withdrawal strategy that simply ratchets spending up with the Consumer Price Index every year can become very demanding on the portfolio if inflation runs hot for several years in a row. Some modern frameworks respond by building in flexible spending rules, such as temporarily capping real spending increases after a market downturn, to reduce the risk of locking in losses, an approach that has been tested in several guardrail‑style studies. Bengen’s 4.7% figure, by contrast, assumes a rigid inflation adjustment, which makes it a useful benchmark but not necessarily the most practical rule for retirees who are willing to adjust their lifestyle in response to market shocks.
Behavioral risks: can investors stick with the plan?
Even if a 4.7% starting rate is mathematically defensible under Bengen’s assumptions, the human side of investing can easily derail the strategy. A portfolio that leans into small‑cap value and maintains a high equity allocation through thick and thin will experience deeper drawdowns and more volatility than a more conservative mix, especially during bear markets. Many retirees find it difficult to keep withdrawing and rebalancing into stocks when their account balance is falling, which can lead to panic selling or ad hoc spending cuts that deviate from the original plan, a pattern documented in several behavioral‑finance reviews of retirement behavior.
There is also the psychological challenge of watching withdrawals rise with inflation even when markets are down, which is exactly what the classic 4% and 4.7% rules prescribe. Some retirees may prefer a more flexible approach that ties spending to portfolio performance, for example by limiting withdrawals to a fixed percentage of the current balance or by using guardrails that trigger adjustments when the withdrawal rate drifts too high or too low. These methods can reduce the risk of running out of money but introduce more variability in year‑to‑year income, a tradeoff that has been explored in depth in modern dynamic‑spending research. The bottom line is that a higher initial rate demands stronger emotional discipline, and not every investor will find that realistic once markets turn rough.
How taxes, fees, and real‑world frictions change the math
Bengen’s headline figures are typically presented in pre‑tax, pre‑fee terms, which is useful for clean modeling but less tidy in real life. Most retirees hold a mix of tax‑deferred accounts like traditional IRAs and 401(k)s, taxable brokerage accounts, and sometimes Roth accounts, each with different tax treatments. A 4.7% gross withdrawal from a heavily tax‑deferred portfolio can translate into a significantly lower net spending amount after federal and state income taxes, especially for married couples whose withdrawals push them into higher brackets, a gap that is highlighted in several tax‑aware planning studies.
Investment costs also matter. While index funds from providers like Vanguard, Fidelity, and Schwab now offer expense ratios as low as 0.03% on broad U.S. equity funds, many investors still hold higher‑cost mutual funds or pay advisory fees of 0.50% to 1.00% of assets each year. Those ongoing costs effectively reduce the portfolio’s net return, which in turn lowers the sustainable withdrawal rate over long horizons. Analyses that layer realistic fee levels onto historical return data often find that a 1% annual drag can cut safe withdrawal rates by several tenths of a percentage point, as shown in fee‑sensitivity research on withdrawal strategies. Anyone eyeing 4.7% needs to adjust that figure for their own tax situation and cost structure rather than assuming the gross number will translate directly into spendable cash.
Using 4.7% as an upper bound, not a default setting
When I put all of these threads together, I see Bengen’s 4.7% figure less as a new rule and more as an updated ceiling under idealized conditions. It tells us that, in U.S. history, a retiree with a specific equity‑heavy portfolio that includes small‑cap value, who commits to a 30‑year horizon and rigid inflation adjustments, could have started withdrawals at roughly 4.7% without exhausting their savings in the worst past scenarios. That is valuable information, especially for investors who are comfortable with higher volatility and who want to understand the outer edge of what has worked historically, as detailed in his latest safe‑rate update.
For many retirees, though, a more cautious starting point may be appropriate, particularly given today’s valuation backdrop, lower bond yields in some periods, and the behavioral and tax frictions that real portfolios face. Several contemporary analyses that blend historical data with current market conditions suggest that a range around 3.5% to 4.0% may offer a better balance between safety and lifestyle for new retirees who want a high probability of success, as summarized in recent market‑aware estimates. In practice, I would treat 4.7% as a number to stress test against, not a default setting: if your plan still looks robust at that level under conservative assumptions, you may have more flexibility than you thought, but if it only barely works on paper, the safer move is to dial back, build in flexibility, and let your spending adapt as markets and your life evolve.
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