Safe Withdrawal Rate and Asset Allocation: What Matters

3.9%. That is Morningstar's current safe starting withdrawal rate for a 30-year retirement. It assumes fixed withdrawals that rise with inflation and money left over in 90% of simulated futures. The research also says the best results came from balanced portfolios holding 30–50% in stocks, not from the most aggressive mixes. If you're working out the link between your safe withdrawal rate and asset allocation, that's the first thing to know. Your mix matters, but probably less than you expect, and the biggest risk is at the cautious end, not the aggressive end.

Source: Morningstar, The State of Retirement Income, December 2025.

Here's what the main studies say, why they seem to disagree, and how to use their findings when you check your own numbers.

The short answer

• A wide middle range works. Most research finds that portfolios with somewhere between about one-third and two-thirds in stocks support similar starting withdrawal rates over 30 years.
• Too little in stocks hurts most. Very conservative portfolios fall behind clearly, because they can't keep up with inflation over a long retirement.
• Other choices often matter more. Your time horizon, how much failure risk you'll accept, and whether you can cut spending in bad years can move your safe rate further than switching from 50/50 to 60/40.

Safe withdrawal rate and asset allocation: what the research says

Each study asks a slightly different question with a different method. Here are their findings side by side:

Sources: Morningstar AU, Chart of the week; Trinity study via Compound Ladder; Pfau, MPRA paper 32973; Portfolio Charts; Marotta on Money.

The top-line answers look different. Trinity seems to favor 75/25, while Morningstar favors something closer to 40/60. But look at the shape of the results and they mostly agree. Both find a broad, fairly flat range in the middle where outcomes are similar, and a steep drop once stocks fall too low.

Why the studies disagree

Backtests vs. forecasts

The Trinity study looks backward. It tests every historical 30-year period of US returns. That history includes a century of strong US stock returns, so higher stock allocations look good.

Morningstar looks forward. It builds its numbers on return forecasts, and current forecasts are more modest for stocks relative to bonds. With those inputs, the extra stock return doesn't pay enough to make up for the extra volatility, so the best mix moves toward balance. Retirement Researcher has a plain-English explanation of how market expectations change safe withdrawal rates.

Neither method is "right." A backtest assumes the future will look like US history. A forecast assumes the forecasters have it roughly right. Knowing which assumption sits behind a number tells you how much to trust it.

The success target

A 90% target and a 100% target are different questions. Aiming for success in every scenario means planning for the worst case, which pulls the starting rate down. Morningstar's analysis shows this clearly (see the Morningstar AU chart). The best allocation can also shift depending on which target you pick.

The time horizon

Nearly every study defaults to 30 years. Longer horizons lower the safe rate and generally call for more in stocks, because inflation has more time to erode a bond-heavy portfolio. If you retire early, or simply live a long time, a 30-year result can flatter you.

Living a long time is not a rare case. Social Security's planning guidance says about one in three 65-year-olds may live to at least 90. (Source: Social Security Administration, Retirement Information for Medicare Beneficiaries, 2026.) That's why the plan you build at Monte Climb runs to age 95 by default, and you can extend it.

Fees, taxes and non-US returns

Trinity's figures are pre-tax, use only US data and ignore fees. Fees and taxes come straight out of what you can spend. Using international return history as well would also likely give more cautious results than US-only backtests. Keep these caveats in mind when you see a headline rate.

The real danger zone: too little in stocks

If you take one thing from the allocation research, make it this: the expensive mistake is being too conservative.

Look at the Trinity numbers again. Going from 75/25 to 50/50 cost about three percentage points of success at a 4% withdrawal. Going from 50/50 to 25/75 cost 24 points. In one advisor's model, an all-bond portfolio supports a starting rate under 3%, and all cash supports roughly 1%.

The reason is simple. Over decades, inflation is a bigger threat than a market crash for a portfolio made of "safe" assets. A retiree who sells stocks out of fear and never buys back in can turn a temporary loss into a permanent cut in income. Marotta's piece is titled around exactly that point: the importance of staying invested.

Glide paths: changing your mix during retirement

Your allocation doesn't have to stay fixed. Some research looks at glide paths, which means shifting your stock share gradually over time.

• Pfau and Kitces (2013) tested 121 linear glide paths. Rising-equity paths, which start conservative and add stocks over time, produced the highest sustainable withdrawal rates. The best ones began retirement at 20–40% stocks and ended at 40–80% (Kitces).
• Kitces's accelerated version moved to 60% stocks over 15 years and then held there. It typically raised the safe rate by 0.1–0.2 percentage points, and by nearly 0.5 in the best cases (Kitces).
• Early Retirement Now's historical tests found the 30%-to-70% rising glide path was "consistently one of the worst" (Part 19, Part 20).

How can both be true? The two approaches stress different things. A rising glide path protects you when markets fall early in retirement, which is when losses do the most damage. In simulations built on typical return assumptions, that protection pays off. In particular historical periods, especially ones where stocks did well early in retirement, starting conservative left money behind. The method decides which risk gets the most weight.

The practical lesson: glide paths are a refinement worth tenths of a percentage point. They aren't a cure-all.

What a success rate doesn't tell you

Nearly every study scores allocations on one number: the share of scenarios where the money lasts. That's useful, but it leaves things out.

• How bad the failures are. Running out at 93 is very different from running out at 78.
• What's left at the end. Two allocations with the same success rate can leave very different amounts for heirs, or for a late-life health care bill.
• How much you'd have to cut back. In bad scenarios, the question is often how much you'd trim spending, not whether you run out.

Health care is a good example. Fidelity estimates a 65-year-old retiring in 2025 will need $172,500 for Medicare premiums, deductibles and prescriptions over retirement. That figure leaves out long-term care entirely. (Source: Fidelity Investments, 2025 Retiree Health Care Cost Estimate, July 2025.) An allocation that looks fine on success rate alone may still leave little room for that.

Flexibility often beats fine-tuning

Here's the finding that should change how you think about your mix. According to Boldin's summary of Morningstar's research, flexible withdrawal methods support noticeably higher starting rates than the 3.9% fixed baseline:

• Guardrails (raise or cut spending when your portfolio crosses set limits): about 5.2%
• Constant-percentage withdrawals (take a fixed percentage of whatever the portfolio is worth each year): about 5.7%

Compare those with the glide path gains measured in tenths of a point. Being willing to spend a little less in a bad year can be worth more than any change to your allocation. The trade-off is that your income varies, so this only works if your budget can handle it. TheStreet's comparison of Fidelity, Morningstar and Bengen shows how much these frameworks differ.

How to use this in your own plan

Put it together and you get a simple way to think it through:

1. Start with a reasonable middle-range mix. The research is broadly comfortable with roughly one-third to two-thirds stocks over 30 years.
2. Avoid the conservative extreme unless you have a specific reason and the numbers still work.
3. Match the horizon to your life, not to a study. If there's a real chance you'll live to 95, plan for it.
4. Choose your success target on purpose. 90% and 100% lead to different spending levels.
5. Decide how flexible you can be. That decision may be worth more than any allocation tweak.
6. Test your own numbers. A published rate is an average across hypothetical retirees. Your savings, spending and age are specific to you.

That last step is what a Monte Carlo simulation is for. Instead of assuming one average return, it runs your plan through many possible market paths, good and bad, and counts how many stay funded. Monte Climb does this with three numbers: your age, your savings and your monthly spending. It runs them through 1,000 simulated futures and gives you a success rate. If the result raises questions, such as "Can I retire at 62?" or "What's a sustainable spend for me?", you can ask William, our AI planner, who shows his work.

It's planning software, not advice. And the result is a probability, not a promise.

Want to see your own odds? Show my answer. Three numbers, 1,000 futures, and it runs in your browser.

Frequently asked questions

What is the safe withdrawal rate in 2026?

Morningstar's research, published in December 2025, puts the safe starting withdrawal rate at 3.9%. That assumes fixed, inflation-adjusted withdrawals over 30 years with money remaining in 90% of simulated outcomes.

Does holding more stocks let you withdraw more in retirement?

Only up to a point. Historical backtests like the Trinity study favor higher stock shares, while Morningstar's forward-looking model found 30–50% stocks supported the highest rates. Most research agrees that a broad middle range works similarly and that very low stock allocations do the most damage.

What asset allocation is best for the 4% rule?

In the Trinity study's US historical data, a 4% withdrawal over 30 years succeeded in 98% of periods with 75/25 stocks/bonds, 95% with 50/50 and 71% with 25/75. Wade Pfau found any allocation from 33% to 70% stocks supported about a 4.3% rate.

Is a rising equity glide path better in retirement?

In Pfau and Kitces's simulations, rising-equity glide paths produced the highest sustainable withdrawal rates. Early Retirement Now's historical tests found one common rising path among the worst. The gains are typically small, around 0.1–0.2 percentage points.

Can flexible spending raise my safe withdrawal rate?

Yes. According to Boldin's summary of Morningstar's research, guardrails supported about 5.2% and constant-percentage withdrawals about 5.7%, compared with 3.9% for fixed withdrawals. The trade-off is that your income varies from year to year.