A Brief History of 4%
In 1994, financial planner William Bengen published a study that looked at every 30-year retirement period since 1926. His finding: a retiree who withdrew 4% of their portfolio in year one, then adjusted that amount for inflation each year, never ran out of money in any historical period.
The "4% Rule" became gospel. Financial planners, retirement calculators, and FIRE community members all adopted it as the safe withdrawal rate. And for a simple, conservative baseline — it still has value.
But retirement planning has changed. And the 4% Rule has some serious blind spots.
Why 4% Falls Short
First, it assumes a fixed 30-year retirement. If you retire at 55 or live to 95, you need 35-40 years. Bengen's original analysis didn't cover periods that long. Second, it ignores taxes entirely. Withdrawing $40,000 from a Traditional IRA is not the same as $40,000 from a Roth — your after-tax spending power could differ by 20-30%.
Third, it treats spending as constant (adjusted only for inflation). Real retirees spend more in early retirement (travel, hobbies), less in mid-retirement, and more again in late retirement (healthcare). The "go-go, slow-go, no-go" spending pattern is well documented.
Finally, current bond yields and market valuations suggest that the next 30 years may look different from the historical periods Bengen studied. Several researchers have argued that 3.3-3.5% may be more appropriate for retirees today.
Modern Alternatives
Guardrails Strategy: Set a base withdrawal rate (say 4%) with upper and lower guardrails (5.5% and 3.5%). If your portfolio grows and your withdrawal rate drops below 3.5%, give yourself a raise. If markets crash and your rate exceeds 5.5%, cut spending temporarily. This adapts to market conditions rather than ignoring them.
Dynamic Percentage: Withdraw a fixed percentage of your current portfolio value each year (e.g., 4% of whatever it's worth now, not 4% of the original). This automatically reduces withdrawals when markets drop and increases them when markets rise.
Spending Phases: Model your spending in 3 phases — Active (ages 65-75, 100% of target), Moderate (75-85, 80%), and Essential (85+, 60% plus higher healthcare). This reflects how retirees actually spend money.
What Sagery Does Differently
We let you choose your withdrawal strategy: fixed, inflation-adjusted (classic 4% Rule), dynamic percentage, or guardrails. Each one runs through our Monte Carlo engine so you can see the success rate, income range, and worst-case outcomes for each approach.
We also model spending phases natively — set your go-go, slow-go, and no-go percentages and see how they affect your 30-year projection. Combined with tax modeling, this gives you a much more realistic picture than a single withdrawal rate ever could.
The 4% Rule isn't dead as a starting point — it's dead as an ending point. Modern planning starts there and builds a strategy that adapts to your life.
📌 Key Takeaways
- 1The 4% Rule was revolutionary in 1994 but assumes fixed spending, 30-year horizons, and no taxes
- 2Real retirees have variable spending patterns (go-go, slow-go, no-go phases)
- 3Guardrails and dynamic strategies adapt to market conditions instead of ignoring them
- 4Current market valuations may warrant a lower starting rate (3.3-3.5%)
- 5The best withdrawal strategy is the one that adjusts to your life — not a fixed rule
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