The financial planning problems that is toughest to plan is when a lot of the variables that goes into the planning are tight.

And also when we have a lot of constraints and scripts.

Back when I need to work with a limit of $500,000 in wealth, I had to consider whether it is feasible if my annual expense is $24,000/yr. (you can read more about it in this article)

This works out to a 4.8% initial withdrawal rate (24k/500k).

Depending on how much you know about the literature of retirement, this would seem very feasible or very not feasible to you.

In hindsight, that withdrawal rate is rather high that if one were to withdraw a constantly inflation adjusted $24,000/yr, there is a high chance the person would run out of money.

To make 4.8% initial withdrawal safe, you will need to:

Ensure you have a high rate of