If your Amazon revenue is up but profit is flat or shrinking, it is almost always one of three things: rising TACoS, fee and COGS creep, or returns and discounting. Growth is supposed to make the P&L look better, not worse — so when it doesn't, the cause is usually hiding in one or two SKUs, not the whole catalog.
This is one of the most common patterns we see, and it is fixable once you can name which of the three is doing the damage. Below: why each happens, how to tell them apart in your own data, and what to do — without cutting the sales that hold your rank. It all rests on knowing your real contribution margin per ASIN.
Quick note: I run a fractional Amazon team, and "revenue's up but where's the money?" is one of the most frequent reasons a brand calls us. The diagnosis is almost always faster than they expect.
The Pattern: Growth That Doesn't Pay
Revenue is a vanity number until it survives the trip down to contribution margin. Plenty of ways to grow the top line actually shrink the bottom one: buying sales with more ad spend, discounting deeper, or adding lower-margin SKUs to the catalog. Each lifts revenue while quietly compressing what every sale contributes.
So the first reframe: profit follows contribution margin, not revenue. If contribution margin per unit is falling faster than volume is rising, scaling just loses money more efficiently. That's why the diagnosis always starts at the ASIN level — the account average hides it.
What makes the pattern so deceptive is timing. Revenue shows up instantly on the dashboard; the costs that erode it — settlement fees, returns processed weeks later, storage charged monthly, a freight invoice that lands next quarter — all arrive on a delay and in different reports. So the growth feels real and immediate while the margin damage accumulates quietly in the background. By the time the bank balance makes the problem obvious, it's usually been building for two or three months. That lag is exactly why you can't manage profitability off the sales chart, and why the brands that catch it early are the ones reconciling contribution margin on a regular cadence instead of reacting when the cash runs thin.
Growing an unprofitable unit economics doesn't fix it. It funds it.
Cause 1: TACoS Is Climbing
The most common culprit. TACoS — total ad spend divided by total revenue — measures how dependent your whole business is on advertising. When revenue holds or grows but TACoS is rising month over month, you're buying sales you used to get for free.
Usually that means organic rank has slipped and ads are backfilling the gap, or campaign structure has drifted — auto campaigns creeping up as a share of budget, no negative-keyword hygiene, bids climbing on terms that no longer convert. The revenue still shows up; it just costs more to get, and the extra cost comes straight out of contribution margin.
Cause 2: Fee & COGS Creep
The quiet one. As you scale and add SKUs, your blended cost structure drifts — and none of it announces itself on the sales dashboard. It shows up only in settlement data.
Individually these are small. Together they can erase a few points of margin a quarter — which, on a business already running a 20–30% contribution margin, is the difference between healthy and underwater.
Cause 3: Returns & Discounting
The one brands underestimate. A return is triple damage: you refund the customer, you often can't resell the unit as new, and on high-return ASINs you may pay a returns processing fee too. Meanwhile, promotions and Subscribe & Save discounts lift units sold — and revenue — while cutting the margin on every one of those units.
If your growth has come partly from deals and coupons, some of your "revenue up" is really "same customers, thinner margin." That can be a fine trade for rank or retention, but only if you've measured it. Most brands haven't.
How to Diagnose Which One
You can usually isolate the cause in an afternoon. Pull the numbers and compare the trend, not the snapshot.
| If you see this… | The cause is likely… | Where to look |
|---|---|---|
| TACoS rising while revenue is flat-to-up | Ad dependency (Cause 1) | Advertising reports; TACoS trend |
| Margin down but ad spend steady | Fee / COGS creep (Cause 2) | Settlement + FBA fee reports |
| Units up, revenue per unit down | Discounting (Cause 3) | Promotions + average selling price |
| One or two SKUs dragging the average | Concentrated — any of the three | Per-ASIN contribution margin |
The single most useful move is to rebuild contribution margin per ASIN and sort by it. The problem is almost never spread evenly — it's one or two SKUs whose economics quietly broke while everyone watched total sales climb. If sales themselves are the concern rather than profit, that's a different diagnosis: see why Amazon sales fall.
The Fix (Without Killing Sales)
Work the movable levers in order, and resist the reflex to just raise prices.
Done in that order, most brands recover meaningful margin from fixes rather than from a blanket price increase that risks the rank they worked to earn. The whole approach is the operating system behind the Amazon profitability playbook — and it's exactly the work a fractional Amazon team runs day to day.
One last discipline: once you've closed the leak, keep watching the same three signals monthly, because they drift back. TACoS creeps up as competition intensifies, fees change with the rate card, and return rates move with the mix — so the brand that stays profitable is the one that treats this as a standing review, not a one-time cleanup.
The takeaway: revenue up and profit down isn't a mystery, it's a diagnosis. Name the cause — TACoS, fees, or returns — fix the movable levers in sequence, and manage the account on per-ASIN contribution margin instead of total sales.
FAQ
It is almost always one of three causes: TACoS is climbing, so a bigger share of revenue is going to ads; fees or landed COGS have crept up and compressed margin per unit; or your return rate and discounting are higher than you think. Calculate contribution margin per ASIN to find which one, because the culprit is usually concentrated in one or two problem SKUs, not the whole catalog.
No. Revenue bought with rising ad spend, deeper discounts, or lower-margin SKUs can grow the top line while contribution margin falls. Profit follows contribution margin, not revenue. Scaling an unprofitable unit economics just loses money faster, which is why per-ASIN contribution margin matters more than total sales.
Compare TACoS (total ad spend divided by total revenue) across the last several months. If revenue is flat-to-up but TACoS is rising, advertising is consuming your margin gains — you are buying sales you used to get organically. That usually means organic rank has slipped or ad structure has drifted, not that ads are inherently too expensive.
The common ones are FBA size-tier increases as you add products, aged-inventory surcharges on slow SKUs, returns processing fees on high-return ASINs, and referral fees on lower-margin items you have added to the catalog. Landed COGS creep from freight and tariffs also compresses margin without ever showing up as an Amazon fee.
Work the two most movable levers first: advertising efficiency (fix campaign structure and lower TACoS without cutting the sales that hold rank) and fees (audit size tiers, aged inventory, and returns). Then re-cost landed COGS and prune or reprice negative-contribution SKUs. Most brands recover meaningful margin from fixes, not from a blanket price increase.