ACoS tells you what a campaign cost relative to the sales Amazon credits to it. TACoS tells you what all your advertising cost relative to everything you sold. The first is a campaign-management number, and it lives in the ads console. The second is an operating expense ratio, and it belongs on the profit and loss view next to referral fees and fulfillment fees, because that is what it is: a cost of selling, expressed as a share of revenue. Sellers who manage the business by ACoS alone can improve every campaign while the business gets worse, and the worked example below shows how.
ACoS. Advertising cost of sales. advertising.amazon.com's guide defines it as ad spend divided by ad revenue, times 100, where ad revenue means the sales Amazon attributes to the ad. A $50 campaign that produced $100 of attributed sales has a 50 percent ACoS. Amazon's guide also states the break-even rule: to hold profit, ACoS has to be lower than profit margin.
ROAS. Return on ad spend, the inverse: ad revenue divided by ad spend. The same guide gives the $100 on $50 example as a ROAS of 2.
TACoS. Total advertising cost of sales: ad spend divided by total sales, including organic. TACoS is a seller-community term, not one Amazon defines on its ACoS guide, and there is no console column for it. You compute it from two sources: spend from the ads console or invoice, and total sales from the settlement or your books.
The denominators are the whole difference. ACoS divides by sales the ad gets credit for. TACoS divides by every sale, credited or not.
Attributed sales and total sales are linked but not locked. If organic sales fall while ad-attributed sales rise, ACoS can improve because the campaign is converting well, and TACoS can worsen because ads are now carrying a larger share of a smaller total. That pattern is common. It shows up when a listing loses organic rank, when a competitor takes the featured offer on organic traffic, or when the seller raises bids to defend a launch and the paid share of sales creeps up month after month.
Illustrative numbers. One SKU, two months.
Month one
Month two
The campaign manager's report says ACoS improved four points. The P&L says advertising went from 10 percent of revenue to 13 percent while revenue fell 13.3 percent. Organic sales dropped $14,000, ad-attributed sales rose $6,000, and the seller spent $760 more to get there. Paid share of sales went from a third to a half.
Now the margin. Suppose margin before ads on this SKU is 28 percent. Month one: $60,000 times 0.28 equals $16,800 of gross profit, minus $6,000 of ads, equals $10,800. Month two: $52,000 times 0.28 equals $14,560, minus $6,760, equals $7,800. Profit fell $3,000, or 27.8 percent, on a SKU whose ACoS got better. The ACoS view says keep doing what you are doing. The TACoS view says something upstream broke and the ads are papering over it.
An account-level TACoS is a blended number. A seller with 40 SKUs at 8 percent TACoS and five launch SKUs at 40 percent will see a 12 percent blend that is true of nothing. The question a seller wants answered, "which products are carrying too much ad cost for the sales they make," only works at the SKU level, and that requires ad spend booked per SKU, not as one advertising line per invoice.
Amazon Ads bills the advertising account, and the invoice does not say which SKU the spend was for. The campaign reports do: each campaign, ad group, and target carries the advertised ASIN. Booking follows from that.
The PPC accounting guide covers the accounting entries, the timing gap between invoice and settlement, and the treatment of ad credits. ConnectBooks posts each Amazon settlement into QuickBooks or Xero at the transaction level, so the revenue side of TACoS is settled revenue by SKU, and the profit reports carry ad cost against SKU-level contribution. ConnectBooks also includes a PPC ROI view built on booked ad cost against sales, which is the per-SKU TACoS picture in report form.
Use ACoS to run campaigns: which keywords, which bids, which placements, whether a specific campaign clears its break-even. Amazon's guide is right that ACoS has to sit below margin, and it is right that it should not be the only metric.
Use TACoS to run the business: whether advertising as a share of revenue is rising, which SKUs depend on paid traffic, and whether an ACoS improvement is a real gain or a symptom of organic decline. TACoS is the number a P&L reader recognizes, because it sits in the same units as every other cost of selling.
Watch the pair together. ACoS down and TACoS up is the pattern in the example. ACoS up and TACoS flat can mean a launch is doing its job and organic is following. Neither number alone tells you which.
The question behind both metrics is "is my advertising earning its keep on this product," and it has a chain of an answer: what changed (spend, attributed sales, organic sales), over which periods, on which SKUs, why, and what to do about it. Crunch, the analytics AI inside ConnectBooks, answers that chain from reconciled data when a seller asks something like "why did ad spend go up on this product without profit going up" or "what did pausing ads on this SKU do to profit." It reads booked ad cost, settled sales, and SKU-level margin. It cannot see inside the campaign (which keyword, which placement), it cannot know that organic rank fell because a competitor launched, and it cannot allocate brand spend that was never assigned to an ASIN. It can tell you that TACoS on this SKU went from 10 to 13 percent while ACoS improved, and that profit fell $3,000 as a result. Where to look next is the console. What to do is yours.
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