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The 4% Rule

research · Bengen's 1994 Safe Withdrawal Rate Study (1994)

Confidence: High

A rule of thumb suggesting that retirees can withdraw 4% of their portfolio in the first year, adjusted for inflation annually, with a high probability of not running out of money over a 30-year retirement.

Core Concepts

The Problem

Many people believe it's a safe, universal guarantee, but it's based on historical US data and may not hold in lower-return environments or longer retirements.

The Claim

The 4% rule provides a useful starting point for retirement income planning but needs to be adapted to individual circumstances, market conditions, and spending patterns.

Key Evidence

  • Historical simulations of US stock and bond returns from 1926 onward show a 95% success rate for a 30-year retirement with a 60/40 portfolio.
  • International data suggests lower safe withdrawal rates in many other countries.

Practical Implication

Financial planners should use the 4% rule as a guideline, not a guarantee, and incorporate flexibility for early retirement or poor market conditions.

Nuance & Limits

The rule fails when retirement lasts more than 30 years or if sequence of returns risk strikes early. Variants like a 'dynamic withdrawal' strategy or lower initial withdrawal rate can increase safety.

Source Material

Citation Density

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