SOP: recalculate break-even ACOS after any fee change

Steps

1. Seller Central → FBA Fee Preview on heroes. Note fulfillment, size tier, storage if relevant, referral.
2. Add live surcharges (fuel 3.5% if on; peak fulfillment in the Oct–Jan window).
3. Add inbound placement amortized per unit if the last shipment paid it.
4. Add low-inventory if that FNSKU is under the live days-of-supply threshold.
5. Drop the stack into the break-even calculator. That % is the exact-campaign ceiling.
6. Update Teikametrics / Xnurta / Cobalt goals per campaign type. Brand defense is not on the same ceiling as generic.
7. Log the old vs new ceiling in the weekly note.

Do not invent a rate card. Fee Preview is the input. The SOP is the sequence.

The formula, said plainly

Break-even ACOS is leftover contribution divided by price: (Price − COGS − Amazon fees − other variable) ÷ price. If advertising cost of sales is higher than that, the ad-attributed order loses money. Recalculate when any fee clock moves: 15 January rate card, 17 April surcharge, 1 October storage, 15 October–14 January peak fulfillment, a new inbound placement line, a low-inventory child. Do not wait until ACOS “feels” high. Feeling is late.

Where the numbers live

Seller Central Fee Preview on heroes: fulfillment, size tier, referral, surcharge, storage if you need it. Profit Analytics if you have it. Last inbound: placement amortized per unit. Inventory Planning: low-inventory if that FNSKU is under the live days-of-supply threshold. Public calculator: break-even ACOS / TACOS. The calculator is arithmetic. Fee Preview is the input. Blogs that publish a full size-tier table are not your catalog.

After the % exists

That percentage is the exact-campaign ceiling, not the brand-defense ceiling. Update Teikametrics / Xnurta / Cobalt goals per campaign type. Log old vs new in the weekly note so automation and humans tell the same story. If a SKU falls under your contribution floor, ranking comes off. Harvest continues. You are not “giving up organic.” You are stopping a donation.

Clocks to rerun this SOP

• 15 January 2026 fulfillment restructure.
• 17 April 2026 fuel/logistics surcharge (MCF/BwP often 2 May).
• 1 October peak storage snapshot.
• 15 October 2026–14 January 2027 peak fulfillment.
• Any inbound that paid placement, any child that tripped low-inventory.

Related: 2026 fee stack, Q4 checklist.

Worked sequence using Fee Preview, not a newsletter

Export Fee Preview on heroes. Write fulfillment, size tier, referral, and any surcharge or low-inventory line. Add last inbound’s placement amortized per unit if you paid a minimal split. Rebuild (Price − COGS − Amazon fees − other variable) ÷ price. That percentage is the exact-campaign ceiling. Brand defense is a different rail. Update Teikametrics / Xnurta / Cobalt the same week and log old vs new so the founder is not surprised in October. If contribution falls under your floor, ranking comes off. Harvest continues. You are not “giving up organic.” You are stopping a donation. Do this again when any clock moves — 15 Jan, 17 Apr, 1 Oct storage, 15 Oct–14 Jan peak fulfillment — not when ACOS “feels” high. Feeling is late.