The ad dashboard looked healthy for nine straight weeks. ACOS sat at 25% the who
By Pasha Knish · October 30, 2026 · Curated by George's Blog
The ad dashboard looked healthy for nine straight weeks.
ACOS sat at 25% the whole time. That was the costume.
Tomorrow is Halloween, so here is the most common costume we find on Amazon accounts: a flat ACOS covering a business that is quietly getting smaller.
ACOS measures ad spend against ad sales. TACOS measures ad spend against total sales. When ACOS holds and TACOS climbs, the ads are not getting worse. Organic sales are leaking, and the ads are buying back sales the listing used to earn for free.
A supplement brand came to us in September with exactly this. Week one of the stretch: $3,000 in ad spend, $12,000 in ad sales, $40,000 in total sales. ACOS 25%, TACOS 7.5%. Week nine: $3,750 in spend, $15,000 in ad sales, $37,500 in total sales. ACOS still 25%. TACOS 10%.
Ad sales grew $3,000 a week. Organic sales fell from $28,000 to $22,500, down almost 20%. Every report the founder saw said the ads were working. They were. They were working to replace rank the hero had lost.
The cause was not in the ad console. A competitor launched at a lower price with a coupon, and the hero slid off page one organically on two of its top three search terms. The ads covered the gap so smoothly that nobody looked.
What we check on every account, every week:
→ TACOS in the same row as ACOS, same font size, in every report.
→ Organic sales as its own line: total sales minus ad-attributed sales.
→ Brand share of impressions on the top 10 search terms in Search Query Performance.
→ When TACOS rises two weeks in a row with flat ACOS, we look at price, reviews, and the listing before anyone touches a bid.
ACOS tells you how efficient the ads are. TACOS tells you whether the business still stands up without them. You need both, and only one of them is on most dashboards by default.
Before you log off for the weekend, pull nine weeks of TACOS next to nine weeks of ACOS.
Costumes are for tomorrow night. Not for the P&L.