The lesson
€40,000 a year turns into €1,000,000 at 4%.
The first input is not the portfolio. It is the annual cost of the life you want to support. At €40,000 a year, dividing by a 4% planning withdrawal rate produces €1,000,000.
Change the rate to 3% and the same €40,000 requires €1,333,333. That €333,333 jump is why a withdrawal rate is not a decorative detail; it is an assumption about uncertainty, time and margin.
The arithmetic does not forecast a safe income. Real planning needs taxes, inflation, pensions, healthcare, family, longevity and the possibility that markets behave badly at the beginning.
