A certain cost today and a conditional rebate later are different kinds of number. Where tracking breaks, and how to weigh a rebate you might not receive.
Cashback is presented as a discount, and arithmetically it looks like one. The difference is certainty and timing. The price you pay is settled at checkout and leaves your account immediately. The rebate depends on tracking working, on the purchase not being returned, on a holding period, and on you completing a payout step weeks or months later.
Subtracting a conditional future amount from a certain present one produces a number that is not comparable to a price, however confidently it is displayed.
Tracking failures are not exotic. They are the ordinary shape of online shopping, and each converts an expected rebate into nothing — usually without telling you.
| Failure | Cause | Would you notice at the time? |
|---|---|---|
| Referral overwritten | Another browser tool claims the click at checkout | No |
| Outside coupon applied | A code from a source other than the programme | No |
| Order edited or part-returned | Basket changed after the click | Not until payout |
| Device switched | Clicked on phone, purchased on laptop | No |
| Session interrupted | Time between click and payment | No |
| Category excluded | Item is in a reduced or zero-rate category | Only if you read the terms |
Headline rates usually apply to a subset of a retailer catalogue. Electronics, gift cards, marketplace sellers and already-discounted items are frequently excluded or paid at a fraction of the advertised rate, and those are precisely the categories where people go looking for cashback.
The rate on the banner and the rate on your purchase are different numbers more often than not.
The honest way to compare a rebate against a price is to discount it by the chance you actually receive it. If a 5% rebate on a 200 dollar purchase is worth 10 dollars, and the realistic probability of it tracking, surviving the holding period and reaching payout is somewhere around three in four, then its comparable value today is closer to 7.50 dollars than 10.
The exact probability is unknowable and varies by programme, retailer and category. That is the point: an unknowable multiplier applied to a known figure produces an estimate, and an estimate does not belong in the same column as a checkout price.
The practical consequence is a simple rule of thumb. A rebate has to be considerably larger than a price difference before it should overturn it, because the price difference is certain and the rebate is not.
A cashback programme and a coupon tool both work by claiming credit for the referral that led to a purchase, and only one referral can be credited. When two are active in the same browser, the last one to act at checkout generally wins, regardless of which actually helped you.
That is worth understanding for your own sake rather than as an accusation about any particular product. If you are relying on a rebate, running a second tool that touches checkout is the single most likely way to lose it. Deciding which one you actually want, and turning the other off for that purchase, is more reliable than hoping they cooperate.
Compare upfront prices first and establish which offers are genuinely close. Only then consider cashback, and only as a tiebreaker between offers that were already comparable on price and delivery.
A larger rebate does not rescue a worse price. If one retailer is meaningfully less expensive before any rebate, that is usually the end of the analysis.
On a purchase you were making anyway, from a retailer you would have chosen anyway, at a price you have already established is competitive, cashback is free money and there is no reason to decline it.
The trap is not cashback. The trap is letting a rebate decide which retailer you buy from before you have compared what they charge.