FBA fees and peak storage as a bid input

Direct answer: FBA fees, referral fees, inbound placement, and peak storage are bid inputs. When the fee table moves, contribution moves, so target ACOS has to move the same week. Do not protect rank on a SKU that no longer clears your margin floor after fees.

What to pull, in order

1. FBA Fee Preview for each hero ASIN (fulfillment + size-tier).
2. Referral fee percent for the category.
3. Inbound placement / low-inventory surcharge if those lines are on the ASIN.
4. Peak storage calendar — Q4 surcharges are not a surprise if you watch the Updates desk.
5. Drop those numbers into the break-even ACOS calculator.

The sequence after a fee notice

This is the same loop we run when Amazon ships a rate card:

1. Recompute contribution after the new fees.
2. Set a hard floor (many catalogs use ~18% contribution after fees — yours may be higher).
3. Cut bids 20–35% on ASINs that drop under the floor. Do not wait for Q4 volume to “make it up.”
4. Leave discovery on a leash. Exact campaigns only scale SKUs that still clear the floor.

Fee amounts change. This page is the operating method. Dated numbers live on Amazon Updates with a source URL. Recalculate whenever a brief lands under Fees.