My income is always greater than my expenses.

The gap is the whole story, and it is a different story from the salary.

Two people can earn wildly different amounts and hold identical gaps. One of them feels wealthy and the other feels hunted, and the difference is usually what happened to their costs the last time their income went up.

That is not a lecture about restraint. Costs rise for reasons nobody chooses — rent, children, illness, a car that finally gave up on a Tuesday.

It is only that the gap decides whether a bad month is an inconvenience or a catastrophe, and it gets a fraction of the attention paid to the figure on the offer letter.