TACoS (Total Advertising Cost of Sales)

TACoS solves a blind spot in standard ACoS reporting: ACoS only measures sales directly attributed to ads, but on Amazon, ad-driven sessions also contribute to organic rank via the CVR-14 channel. A campaign with a 40% ACoS but a falling TACoS is doing exactly what you'd want — burning some ad margin in exchange for organic rank lift that pays out over time. A campaign with a stable ACoS but a rising TACoS is the opposite: ad spend is growing faster than organic sales, which usually means the listing's underlying conversion economics aren't strong enough to convert the extra impressions into lasting rank.