Retirement Withdrawal Strategies
The 4% Rule (Bengen Rule)
William Bengen's 1994 study found that a 4% initial withdrawal rate (adjusted for inflation annually) survived all 30-year periods in US history. The Trinity Study (1998) confirmed this. In 2026, with higher bond yields and lower equity valuations, some researchers suggest a 4.5-5% starting point may be sustainable. Caveat: the 4% rule assumes a US-only portfolio and a 30-year retirement. For longer retirements (early retirement), the success rate drops.
Variable Percentage Withdrawal (VPW)
VPW adjusts withdrawals based on portfolio performance and remaining life expectancy. Developed by finiki for Canadian retirees. Withdraw a percentage of your portfolio each year based on your age. The percentage increases as you age. VPW never depletes the portfolio completely, but withdrawals can vary significantly year-to-year. VPW requires a stable pension (Social Security, annuity) to cover base expenses — the variable portion covers discretionary spending. VPW amortizes the portfolio over remaining life expectancy using a 5% discount rate (or current yield on long-term bonds). The VPW table gives percentages ranging from ~4.0% at age 60 to ~10% at age 95.
Guyton-Klinger Decision Rules
Jonathan Guyton and William Klinger developed rules that allow higher initial withdrawal rates (5-6%) while maintaining safety. Key rules:
- Withdrawal Rule: Start at 5-6% of portfolio. Withdraw that dollar amount (adjusted for inflation) annually.
- Portfolio Management Rule: Maintain a 65/35 stock/bond allocation with a 10% cash buffer.
- Decision Rules: Adjust the inflation adjustment based on portfolio performance. If the portfolio return is negative, skip inflation adjustment. If the withdrawal rate exceeds 120% of the initial rate, cut the withdrawal by 10%.
CAPE-Based Withdrawal
Adjust the withdrawal rate based on Shiller CAPE (Cyclically Adjusted P/E ratio). When CAPE is high (valuations expensive), reduce withdrawals. When CAPE is low, increase them. One formula: withdrawal rate = (5 / CAPE) * 1.5 + 1.5%. At CAPE 30: (5/30 * 1.5) + 1.5 = 2.5%. At CAPE 20: (5/20 * 1.5) + 1.5 = 3.75%. At CAPE 15: (5/15 * 1.5) + 1.5 = 5.0%.
Yield Shield Strategy
Live off portfolio income (dividends + interest) without selling principal. Requires a large portfolio relative to spending. In 2026, a 60/40 portfolio yields ~2.5-3.0% — so you'd need 33-40x expenses. Higher with a dividend-focused portfolio. The yield shield avoids sequence risk because you never sell shares in a down market.
Endowment Model (Spending Rule)
Used by university endowments. Withdraw a fixed percentage (typically 4-5%) of the trailing 3-year average portfolio value. This smooths withdrawals and adjusts automatically to market conditions. The smoothing can be 3-year, 5-year, or using the "70/30 rule" — 70% of last year's spending + 30% of the target rate applied to the current portfolio.
Floor-and-Upside Strategy
Create a "floor" of guaranteed income (Social Security, pensions, annuities, TIPS ladder) covering essential expenses. The remaining portfolio is invested for growth and provides discretionary spending. This is the approach recommended by many financial planners — it separates survival from lifestyle spending.
Comparison Table
| Strategy | Initial Rate | Adjustment | Best For | Success Rate (30yr) |
|---|---|---|---|---|
| 4% Rule | 4.0% | Inflation (fixed) | Simplicity | ~95% |
| VPW | 4-5% | Market + age | Flexible spenders | ~99% |
| Guyton-Klinger | 5-6% | Market rules | Higher spending | ~90-95% |
| CAPE-Based | 2.5-5% | Valuations | Risk-aware retirees | ~99% |
| Yield Shield | Income only | Market | Capital preservation | ~99% |
| Endowment | 4-5% | 3yr avg | Smooth spending | ~95% |