The 4% Rule Is Dead — Here's What's Replacing It

A quick history of the 4% rule

In 1994, financial planner Bill Bengen analyzed historical U.S. stock and bond returns and concluded: a retiree who withdraws 4% of their starting portfolio, then adjusts that dollar amount upward for inflation each year, would not run out of money over any 30-year retirement since 1926 — even retirees who started right before the Great Depression.

This was a breakthrough. Suddenly retirees had a number.

Why it's been challenged

• Bond yields collapsed for two decades, making the bond half of the portfolio drag.
• Stock valuations stayed elevated, suggesting lower forward returns.
• Life expectancy increased — a 65-year-old couple now has a 50% chance one of them reaches age 92.
• Sequence-of-returns risk matters more than expected: a bad first 5 years can sink a 30-year plan.

Subsequent research (Morningstar 2024, Wade Pfau) put the "safe" rate closer to 3.3–3.9% for a 30-year horizon. Some early-retirement researchers argue 3% for a 40-year horizon.

The guardrails approach

Rather than a fixed withdrawal, the Guyton-Klinger guardrails method adjusts spending dynamically:

• Start with a 5% initial withdrawal.
• Define an upper guardrail: if the withdrawal rate (your annual spending ÷ current portfolio) exceeds 6%, cut spending 10%.
• Define a lower guardrail: if the withdrawal rate falls below 4%, raise spending 10%.
• Adjust spending for inflation each year, but skip the inflation raise after a year of negative returns.

In Monte Carlo simulations, the guardrails approach allows higher average spending than the 4% rule with similar success rates — at the cost of accepting that spending will move with markets.

A worked example

Start: $1,000,000 portfolio, $50,000 initial spending (5%).

Year 5: market crash. Portfolio drops to $700,000. Spending is still $50,000 (inflation-adjusted to $54,000). Withdrawal rate = $54,000 / $700,000 = 7.7% — above the 6% upper guardrail. Cut spending 10% to $48,600.

Year 10: market recovers. Portfolio is now $1,400,000. Spending has grown with inflation to $56,000. Withdrawal rate = 4.0% — at the lower guardrail. Raise spending 10% to $61,600.

You get higher lifetime spending than a rigid 4% would have allowed, with similar safety.

The bucket strategy

Pairs naturally with guardrails. Hold:

• Bucket 1 (1–2 years of spending) in cash and short Treasuries. Refill annually.
• Bucket 2 (3–7 years) in bonds and conservative balanced funds.
• Bucket 3 (8+ years) in stocks.

In a down market, spend Bucket 1 and don't sell stocks. In an up market, refill the cash bucket from gains. This isn't magic — the math is similar to a balanced portfolio — but it makes the behavior easier to follow because you're never "selling stocks at a loss."

Annuities as a partial floor

A growing body of research recommends using a single premium immediate annuity (SPIA) to cover essential expenses (housing, food, utilities, healthcare) and investing the rest. With essentials guaranteed, the investment portfolio can tolerate more volatility — and you can afford a higher withdrawal rate on what's left.

Social Security IS your inflation-protected annuity

For most retirees, delayed Social Security is the cheapest annuity on the market. Delaying from 67 to 70 costs roughly 8% per year of foregone income — and buys an 8% per year higher lifetime, inflation-adjusted benefit. No commercial annuity comes close.

Bottom line

A modern retirement plan is dynamic spending + bucketed assets + delayed Social Security as your inflation floor, not a single percentage. The retirees who run out of money are usually the ones who refuse to adjust spending after a downturn — guardrails make that decision for you.