1. The Core Idea It's a heuristic, not a law. You invest a lump sum (The Egg). You withdraw 4% in Year 1. You increase that amount by inflation every year. Historically, this lasts 30 years.

2. The "Golden Egg" The egg is the capital. You eat the growth, not the goose. If you kill the goose (withdraw too much early), the math fails.

3. The Assumptions

• Asset Allocation: Typically 50-75% stocks, the rest bonds. No cash under the mattress.
• Horizon: Designed for 30 years. If you are FIRE (40+ years), 4% is risky. Many use 3.5%.

4. The Takeaway Annual Spend x 25 = Required Capital.
It is a starting assumption, not a promise. Flexibility is the only guarantee.