Income, Expenses, and Cash Flow
Plain English
Income is money coming in. Expenses are money going out. Cash flow is what's left after expenses — positive cash flow means you have money available to save or invest; negative means you're spending more than you earn.
What is it?
Income is money received, typically from employment, self-employment, investments, or benefits. Expenses are money spent, usually split into fixed (rent, loan payments) and variable (groceries, entertainment). Cash flow is income minus expenses over a period of time.
Why does it matter?
Nearly every other financial decision — how much to save, whether you can afford a purchase, how quickly you can pay down debt — depends on understanding your actual cash flow, not just your income.
How does it work?
Tracking cash flow usually means listing income sources and categorizing expenses over a consistent period (commonly monthly), then comparing the totals. Many people are surprised by variable or infrequent expenses (irregular bills, annual subscriptions) that don't show up in a quick mental estimate.
Risks and limitations
Cash flow tracking based on a single month can be misleading if that month had unusual income or expenses. It's generally more reliable averaged over several months. It also doesn't capture non-cash factors like unrealized investment gains or losses.
Questions to ask a professional
Am I tracking cash flow over a long enough period to see irregular expenses? Are there expenses I'm not accounting for (annual fees, occasional repairs)?