Does the 4% Rule Still Work? What the Research Says in 2026

Back in 1994, a financial planner named William Bengen asked a simple question. What's the highest rate a retiree could have pulled from a balanced portfolio at the start of retirement, raised with inflation every year, and never run out over 30 years, even in the worst period of U.S. market history? The answer came out a little over 4%. The Trinity study backed it up a few years later, and "the 4% rule" became the most quoted number in retirement planning. Three decades on, people keep asking whether it still holds.

What the rule actually says

It's a description of a worst case, not a recommendation. Take a retiree who started with $1 million, withdrew $40,000 in year one, and raised that amount with inflation every year no matter what the market did, holding roughly half stocks and half bonds. That retiree wouldn't have run out in 30 years starting from any year since 1926. Not 1929, not 1966, not 1973. In most starting years they'd have finished with more than they began with. The 4% figure is simply the rate that survived the single worst start.

Three assumptions are baked in. A 30-year horizon. Zero flexibility, so spending rises with inflation even if the portfolio halves. And U.S. historical returns, which were higher than most of the world's over that period.

The case that it's too high

Critics point to three things. Bond yields in the 2010s sat far below historical averages, which dragged down the expected return on the safe half of the portfolio. Stock valuations at several recent points have been high by historical standards, and high valuations have historically preceded lower returns. And a retirement that starts at 55 or 60 needs the money to last 35 or 40 years, not 30.

Morningstar's annual research on safe withdrawal rates has put the figure for a 30-year retirement between 3.3% and 4.0% in recent years, depending on the year of the study and what it assumes about future returns. Studies using global rather than U.S. data find lower rates, around 3% to 3.5%, because most countries' markets did worse than America's. Fees matter too. A 1% total cost knocks something like 0.3 to 0.4 percentage points off the sustainable rate.

The case that it's too low

Bengen himself has since argued that 4% is conservative. Adding small-cap stocks and other diversifiers to his original model pushed his historical safe rate to around 4.5% or higher. And the rule's central assumption, that a retiree would keep raising spending straight through a 50% market decline, describes almost nobody we've ever met. Real people cut back in bad years. Research that allows even modest flexibility, like skipping the inflation increase after a losing year, raises the starting rate and lowers the failure risk at the same time.

Then there's the ending balance. Because the rule is set to survive the worst case, in the median case it leaves a large estate. A retiree who follows 4% rigidly through an average 30 years typically dies with more than they started with. Whether that's a feature or a failure depends on whether they wanted to leave that much.

What we take from the research

Four things hold up across every version of the studies.

The starting rate is a range. Somewhere between 3.5% and 4.5% for a 30-year horizon. Lower for longer horizons, higher for shorter ones or for retirees whose essentials are already covered by guaranteed income.

The first decade decides most of it. Every failure in the historical record came from a bad early sequence. So the order of returns matters more than the average, and defending against it is the core of any withdrawal plan.

Flexibility beats precision. A plan that can flex spending by 10% in a bad year supports a higher starting rate than a rigid one, and it fails less often. The mechanism is spending guardrails: a starting rate, plus pre-agreed triggers for raising or cutting.

The portfolio has to hold real growth assets. Every safe-rate study assumes a substantial stock allocation, usually 50% to 75%. A retiree sitting in 20% stocks doesn't have a 4% rule. They have a 2.5% rule and an inflation problem.

What the rule doesn't address

The 4% rule tells you roughly how much a portfolio can support. It says nothing about where the money comes from, and that's where most of the tax value in retirement lives. A retiree drawing 4% from a traditional IRA, a taxable account, and a Roth in the right proportions each year, filling low brackets and watching Medicare thresholds, keeps far more of that 4% than one who draws it in the wrong order. The withdrawal sequence and the Social Security claiming decision are separate from the spending rate, and they often matter more.

Where we come in

We use the 4% range as a first sanity check. Does this portfolio, plus Social Security and any pension, plausibly support this household's spending? If the answer is clearly yes, the work shifts to tax and sequencing. If it's close, the work shifts to the levers: Social Security timing, spending flexibility, part-time income, the allocation. Then we replace the rule with a real plan, meaning a year-by-year projection with guardrails, stress-tested against bad early sequences, and revisited every year. The 4% rule is a good place to start the conversation and a poor place to end it. It's the first page of a retirement income plan, not the last.

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Joseph G. Valerio, CFP®, EAFounder and Lead Advisor at Valerio Wealth Management, a fee-only, fiduciary virtual family office in Miami, Florida. One advisor, credentialed in both financial planning and federal tax. About Joseph

This article is general education, not individualized advice, and it is not tax, legal, or accounting advice. Figures reflect federal law for the year stated and can change. Valerio Wealth Management does not prepare or file tax returns. Speak with a qualified professional about your own situation before acting.