What does TACoS mean on Amazon?

TACoS vs ACoS

Same numerator, different denominator. ACoS divides ad spend by advertising attributed sales. TACoS divides the same ad spend by total sales.

ACoS tells you whether the advertising was efficient. TACoS tells you whether it mattered. They can move in opposite directions, and when they do it is usually the most informative thing on the report.

How to read the two together

Falling TACoS with stable ACoS is the pattern you want. Advertising is holding its efficiency while organic sales grow underneath it, so each rupee of ad spend is carrying more total revenue than it used to.

Rising TACoS with a good ACoS means advertising is efficient but is taking over more of your revenue. Sometimes that is a deliberate launch push. Sometimes it means your organic ranking is slipping and ads are quietly covering for it.

Flat TACoS and flat total sales is the treadmill. The advertising is running well and the business is not moving, which is a well managed way to stand still.

The same term outside Amazon

TACoS is an Amazon-native metric and it travels badly. Outside the marketplace, marketers usually reach for blended RoAS or blended CAC, which ask the same question in different clothes: what is total marketing spend doing against total revenue, rather than against the slice a platform is willing to claim credit for.

In e-commerce generally, if somebody says TACoS they almost always mean the Amazon definition above.