Cash-back / rebate app.

In plain English

A cash-back or rebate app returns a slice of your spending, often 1 to 5 percent, when you shop through it or link a card at partner retailers. The reward is real money, paid out once it adds up to a threshold. The catch is behavioral: these apps are marketing tools designed to send you to specific stores and to spend, so the rewards can quietly encourage buying you would not otherwise do. Used on purchases you were already going to make, they are a small bonus; used to justify extra spending, they cost far more than they return.

01Why it matters

Cash back is real money on planned purchases, but the same apps are built to nudge extra spending, so whether they help or hurt depends entirely on your behavior.

02The math, step by step

A 2 percent app returns 2 dollars per 100 dollars spent. But if it nudges you to spend an extra 100 dollars a month you did not need, that 1,200 dollars a year invested at 7 percent would have grown to roughly 113,000 dollars over 30 years, far more than the cash back.

03What this is NOT

04Receipts

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