Days Not Working

The measure that matters most is the one nobody puts on a balance sheet: the number of days you could live without working. Call it runway, call it FU money — it is the number that determines whether you negotiate from strength or from fear.

The arithmetic has to respect the difference between a stock and a flow. Your liquid assets are a pool measured in dollars; your passive income and your expenses are rates measured in dollars per day. You cannot add a pool to a rate. What you can do is drain the pool at the net rate:

Written this way the formula says something the additive version could not. As passive income approaches expenses, the denominator approaches zero and the runway goes to infinity. That is not a rounding artifact — it is the definition of financial independence, and it falls out of the arithmetic rather than having to be asserted alongside it.

Two consequences worth sitting with. First, the denominator is a difference, so cutting $1,000 a month of spending does exactly as much for your runway as adding $1,000 a month of dividends — and the spending cut is available today, requires no capital, and is not taxed. Second, runway is far more sensitive to your expense base than to your asset base: doubling liquid assets doubles your days, but cutting the gap between expenses and passive income in half also doubles them, and is usually the cheaper move.

Use liquid assets in the numerator — cash, taxable brokerage, anything you could sell in a week without a penalty. Retirement accounts do not belong there before 59½ unless you have actually built the access plan in section “Tax-Efficient Decumulation”.