If your Amazon sales are up but profit is down, the cause is almost always one of five things: ad spend growing faster than organic sales (rising TACOS), FBA and storage fees you are not tracking per unit, a low conversion rate that makes every click more expensive, price cuts and deals that buy volume with margin, or returns and lost inventory nobody reconciles. Revenue hides all five. Profit per unit exposes them.

The fix is not "spend less on ads." The fix is finding which of the five is eating your margin, and fixing the root cause.

I have looked at this problem in more than 200 Amazon accounts. Here is how to diagnose it in an afternoon.

Why does revenue go up while profit goes down?

Because Amazon makes it easy to buy revenue.

You can raise bids and sales go up. You can run a deal and sales go up. You can send more inventory and sales go up. Every one of those moves has a cost that shows up later, and usually somewhere else in your P&L.

Seller Central shows you sales on the home screen. It does not show you profit per unit. So most founders watch the number that is going up and miss the one that is going down.

Revenue growing while profit is flat is not a win. Margin is the only real metric.

What are the 5 most common causes?

1. Your TACOS is climbing

TACOS is total ad spend divided by total sales (ads plus organic). If sales grow 20% but ad spend grows 50%, your TACOS goes up and your profit goes down, even though the dashboard looks great.

Here is the important part. TACOS is a symptom, not the problem. When TACOS climbs, it usually means your organic sales are not growing with your ad sales. Amazon is not ranking you higher for the sales you are buying. That points to a listing, conversion or keyword problem, not a bid problem.

One client, ORLO, came to us at 30% TACOS. We did not just cut bids. We fixed brand clarity and keyword targeting so the ads fed organic rank. TACOS went to 5%, and revenue grew 25% at the same time.

2. Fees are growing faster than price

2026 has stacked fees on top of each other. Here is what an FBA seller is paying in Q4 2026:

• Base FBA fulfillment fees rose an average of $0.08 per unit on January 15, 2026 (Amazon).
• A 3.5% fuel and logistics surcharge on fulfillment fees since April 2026 (DAM Law Firm summary of Seller Central notices).
• A peak fulfillment fee averaging about $0.32 per unit, from October 15, 2026 to January 14, 2027. It is based on ship date, not order date.
• Peak storage for standard-size items at $2.40 per cubic foot per month from October to December, vs $0.78 off-peak.
• Some ASINs move to a different fee category from October 31, 2026, which can change your referral fee without any visible change on the listing (Novadata, October 14, 2026).

On a $25 product with a 20% margin, $0.60 to $0.70 in extra per-unit fees is roughly 12 to 14% of your profit on that unit. Gone. Quietly.

3. Your conversion rate is too low

This one hides inside PPC. If your listing converts at 8% and your competitor converts at 16%, you need twice the clicks to get the same sale. Same CPC, double the cost per order.

Most brands try to fix this with bids. You cannot bid your way out of a listing that does not convert. Necklifters went from $10K to $50K a month. The first thing we fixed was not ads. It was the messaging and differentiation on the listing. Then we scaled.

4. You are buying volume with discounts

Coupons, Lightning Deals, Prime-exclusive discounts, price matching a cheaper competitor. Each one adds units. Each one takes margin. Stack a 20% coupon on a deal on a product with 25% net margin and you are close to breaking even on every unit sold.

I started on Amazon in 2016 with a scratch-off world map. The cheap versions were everywhere. We went premium and made $150K profit in year one with one product. Price is almost never the real lever. Competing on price is a losing game.

5. Returns, lost units and reimbursements nobody checks

Amazon loses and damages inventory. Customers return items that never get restocked. Sometimes you get reimbursed. Sometimes you do not, unless someone files a claim. On a growing account this leak grows with you, because more units means more units lost.

How do I check this in Seller Central?

Do this once. It takes 2 to 3 hours. You will know exactly where your margin is going.

• Step 1: Get true profit per ASIN. Go to Reports > Payments > Date Range Reports. Pull the last 90 days and the same 90 days last year. Compare total sales vs net proceeds. If sales grew more than net proceeds, the leak is real.
• Step 2: Calculate TACOS by month. Total ad spend from the Advertising Console divided by total ordered product sales from Reports > Business Reports > Sales and Traffic. Plot 12 months. If the line goes up while organic share goes down, ads are carrying you.
• Step 3: Check organic vs paid share per keyword. Brand Analytics > Search Query Performance. For your top 10 queries, compare your click share and purchase share to your impression share. High impressions with low purchase share means a conversion problem, not a visibility problem.
• Step 4: Check conversion rate per ASIN. Business Reports > Detail Page Sales and Traffic by Child Item. Look at Unit Session Percentage. Under 10% in most categories is a listing problem.
• Step 5: Audit fees per unit. Reports > Fulfillment and the Fee Preview report. Check the size tier and fee category of every top ASIN. Wrong size tier or wrong fee category is common. With the October 31 category changes, check it now.
• Step 6: Check storage. Inventory > FBA Inventory and the Monthly Storage Fees report. Any ASIN with more than 90 days of cover in Q4 is paying peak storage for nothing.
• Step 7: Check reimbursements. Reports > Fulfillment > Reimbursements and Inventory Ledger. Compare units lost or damaged vs units reimbursed.

What is a healthy TACOS on Amazon?

It depends on margin and product stage, so be careful with any single number. As a rule of thumb from what we see:

• Launch phase (first 3 to 6 months): 20 to 35% TACOS can be fine if organic rank is climbing.
• Established product: 8 to 15% is typical for a healthy brand.
• Strong brand with real organic rank: under 10%, sometimes much lower.

The real test is the trend. TACOS should go down over time as organic rank builds. If it only goes up, ads are not building anything. They are renting you sales.

How do I fix it?

In order. Fix the cheapest leaks first, then the structural ones.

• Week 1 to 2: Cut wasted spend. Search Term Report, last 60 days, every term with clicks and zero sales above your break-even click count. Negate. Fix fee category and size tier errors. File reimbursement claims.
• Week 3 to 6: Fix conversion. Main image, title, first two bullets, A+ content. Read your competitors' 1 and 2 star reviews. That is where the buyer tells you what they actually want.
• Week 6 to 12: Restructure PPC so it supports organic rank on the keywords that convert, not the biggest keywords in the niche. Track organic rank weekly. Watch TACOS drop as organic grows.

Zelmins went from $40K to $75K a month at 20% net profit with this order of operations. Growth and margin at the same time is possible. It just does not come from turning up the budget.

Common mistakes (and what most agencies get wrong)

• Cutting ad spend across the board. Revenue drops, rank drops, and you are worse off. Cut waste, not spend.
• Reporting ACOS instead of TACOS. ACOS only looks at ad sales. A low ACOS on branded keywords can hide a bleeding account. Most agency reports lead with ACOS because it looks better.
• Treating PPC as the goal. PPC is a tool. Organic ranking is the goal. If your agency's plan is "more campaigns," that is not a plan.
• Ignoring fees because "Amazon sets them." Amazon sets the rate. You control size tier, fee category, inventory levels and inbound choices.
• Discounting to hit a sales number. Hitting a revenue target at break-even is not a win. It is a busy month.
• Sending reports instead of fixes. A dashboard telling you TACOS went up is not a diagnosis. Find the cause, fix it, measure it.

FAQ

Why is my Amazon revenue growing but my profit isn't?

Usually because ad spend, fees or discounts are growing faster than sales. Check TACOS by month, fees per unit, and conversion rate per ASIN. In most accounts one of those three explains most of the gap.

What is the difference between ACOS and TACOS?

ACOS is ad spend divided by ad sales. TACOS is ad spend divided by total sales, including organic. TACOS tells you how dependent your business is on ads, which is why it is the better profit metric.

How do Amazon's Q4 2026 fees affect my profit?

From October 15, 2026 to January 14, 2027 most FBA units carry a peak fulfillment fee averaging about $0.32 per unit, plus the 3.5% fuel and logistics surcharge. Peak storage runs $2.40 per cubic foot per month for standard-size items from October to December. Keep inventory lean but avoid stockouts, and check your fee categories before October 31.

Should I lower my prices to grow sales on Amazon?

Rarely. Lower prices buy volume with margin and train buyers to wait for discounts. Better conversion, better positioning and real differentiation grow sales without giving up profit.

How long does it take to lower TACOS?

Wasted spend can be cut in the first 2 to 4 weeks. Real TACOS reduction comes from organic rank growth, which typically takes 60 to 90 days of consistent conversion and sales velocity.

Where can I see profit per product in Seller Central?

Seller Central does not show net profit per ASIN directly. Combine the Date Range Reports in Payments, the Fee Preview report, ad spend per ASIN from the Advertising Console, and your own landed cost per unit.

Want someone to find the leak for you?

We run a free Clarity Call. We go through your PPC, fees, listings and organic rank, show you every leak we find, and give you an ROI projection. No pitch until you have seen the numbers.

Book it at globious.io.