When Amazon prepped your inventory, a labeling mistake was Amazon's problem to fix. That safety net is gone. The prep center you pick now sits between your supplier and your Buy Box, and its mistakes arrive on your account as suppressed listings, unfulfillable inventory, and reimbursement claims you have to argue for.
Most sellers vet a prep center with two questions: what do you charge per unit, and how fast do you receive? Both are reasonable questions and neither is a good place to start. Price is meaningless until you know what is bundled into it, and a fast receiving promise is worth nothing without a written consequence for missing it.
Below are twenty questions worth asking before a single carton leaves your supplier. They are ordered roughly the way a shipment moves: does this company exist, can it do the work, what happens when something goes wrong, what does it really cost, and how do you leave.
Before you talk about price
1. Confirm the facility physically exists
Ask for the warehouse address and look at it on satellite view. You are checking for a loading dock. A surprising number of prep operations run out of a residential garage, a self-storage unit, or a mailbox rental that forwards to somebody's kitchen table. None of those can receive a 40-foot container, and none of them survive your first pallet-sized inbound.
Ask for a photo of the dock with today's date, or a short video walkthrough. An operator with a real building will send it in ten minutes. Hesitation here is the answer.
2. Verify the legal entity, not the brand name
The brand on the website is often not the company that will hold your goods. Ask for the registered legal name, the state of registration, and the entity's standing in that state's business registry. Then check that the name on the contract, the name on the invoice, and the name on the insurance certificate all match.
When they do not match, you have no idea which entity you would be suing, and neither will your lawyer.
3. Get a certificate of insurance with your name on it
Not a screenshot of a policy summary. A certificate of insurance issued by their broker, listing you as an additional insured or at minimum as a certificate holder. You want to see two things on it: commercial general liability, and either warehouse legal liability or a cargo policy that covers goods in their care, custody, and control.
General liability alone does not cover your inventory. It covers someone slipping in their parking lot.
Can they actually do Amazon work?
This is where a generic 3PL and a real prep center separate. Ask these as open questions and let them explain. You are listening for whether the vocabulary is fluent or rehearsed.
4. FNSKU labeling and label placement
Ask how they handle Amazon barcodes: where the label goes, what they do when the manufacturer's barcode has to be covered, and how they prevent two barcodes from being scannable on the same unit. A unit with two live barcodes is a receiving error waiting to happen.
Also ask what their label error rate is and how they measure it. An operator who has never measured it does not have one.
5. Polybagging, suffocation warnings and bundling
Ask when they add a suffocation warning. The answer should reference the bag opening size — any bag with an opening of five inches or more needs the warning printed or applied. Ask how they handle bundles and multipacks, and specifically how they make a bundle arrive as one unit rather than as parts a warehouse associate can separate.
6. Expiration dates and lot control
If you sell anything consumable, topical, or ingestible, this question decides the relationship. Ask what date format they print, whether the date goes on the unit and the carton, and how they segregate lots so a first-expiring lot ships first. Ask what they do when a supplier's carton has a date format that does not match what Amazon expects.
An operator who has handled a recall will tell you about lot traceability without being asked.
7. Box content information and inbound shipping plans
Ask who creates the shipment plan: you, or them. Then ask how box content information gets submitted, and whether they submit it as a feed or type it in. Manual entry at scale is where per-unit fees appear on your Amazon invoice for no reason.
Also ask whether they use Amazon's partnered carrier rates or their own freight. Both are defensible. Not knowing the difference is not.
Receiving: where money quietly disappears
8. Get the receiving SLA in business days, in writing
"We receive fast" is not an SLA. You want a number of business days from carrier delivery to units checked in and available, and you want it in the agreement rather than in an email.
Then ask the question that matters more: what happens when they miss it? If the answer is an apology, the SLA is decorative. Reasonable operators will offer a credit, or at least name a specific escalation contact.
9. Ask what happens when the supplier ships it wrong
Your supplier will eventually send unlabeled cartons, the wrong quantity, or a case pack that does not match the purchase order. This is not an edge case, it is Tuesday.
Ask what the prep center does at that moment. The good answer is that they stop, photograph, and contact you before touching anything, with a named person and a response window. The bad answer is that they improvise and tell you later, or that they bill an unquoted hourly rate to sort it out.
10. Ask who is allowed to open a carton
Specifically: can a warehouse associate decide on their own to open, repack, or re-label your goods without written approval? You want the answer to be no, with an exception for damage inspection that gets documented.
Discrepancies, damage and who eats the loss
11. The count-discrepancy protocol
When their count differs from your purchase order, whose number wins? Ask for the process in steps: who recounts, whether it is recorded on video, how the discrepancy is reported to you, and how long you have to dispute it before their count becomes final.
The last part is the trap. Some agreements give you 48 hours from a report you were never told to look for.
12. Damage liability and photo evidence
Ask whether they photograph inbound pallets before breakdown. Without that photo there is no way to establish whether damage happened in transit or in their building, which means the carrier blames the warehouse, the warehouse blames the carrier, and you absorb it.
Ask how long they retain those photos and whether you can access them yourself.
What "per unit" actually includes
13. Unbundle the per-unit price
Take their headline per-unit rate and ask which of these it covers: the FNSKU label, the polybag, the bubble wrap, the box, the tape, the suffocation warning, and the labor to apply all of it. Ask for the price of each item that is not included.
A higher all-in rate beats a low rate with six line items under it, and you cannot compare two quotes until both are expressed the same way.
14. Storage: the unit of measure is the whole game
Storage quoted per pallet, per bin, per shelf, and per cubic foot are not comparable numbers. Ask which one they use, what a "pallet" means in their building — footprint only, or footprint and height — and whether a partial pallet bills as a full one.
Then ask about the free-storage window after receiving, what the rate becomes after it, and whether long-dwelling inventory escalates.
15. Minimums, setup fees and the true monthly floor
Ask for the minimum monthly spend, any account setup or onboarding fee, and whether the minimum applies in a month when you ship nothing. Add it up and you have your real fixed cost, which is the only number that matters when you are modeling a slow quarter.
Liability: read the cap, not the promise
16. Find the per-shipment liability cap
Every warehouse agreement has one, and it is usually far below the value of your inventory. Common structures cap liability at a fixed amount per shipment, or at a multiple of the handling charge for the affected goods. A cap tied to their handling fee can mean a lost pallet is worth a few dollars to them.
Find the number. If your typical inbound is worth more than the cap, either negotiate it up, insure the gap yourself, or accept the exposure knowingly.
17. Check whether they cover cost or retail
A policy that reimburses at your landed cost and one that reimburses at market value produce very different outcomes on a lost shipment. Ask which, and ask what documentation they require to prove value. Supplier invoices are usually accepted; Amazon listing screenshots usually are not.
Systems, capacity and the calendar
18. Portal, API, or email and spreadsheets
Ask to see the client portal before you sign, with a live demo rather than a screenshot. You are checking whether you can see inbound status, on-hand quantities, and outbound tracking without emailing anyone.
If the operation runs on email threads and a shared spreadsheet, that can still work at low volume. It stops working at exactly the moment you get busy, which is the moment you can least afford it.
Also ask which channels they support beyond FBA. If you plan to add Walmart, TikTok Shop, or direct-to-consumer, ask now rather than after you have integrated.
19. Q4 capacity and intake caps
Ask what happened in their building last Q4: how much volume they handled, whether they capped intake, and whether any client got told to hold shipments. Then ask what their capacity ceiling is in pallets and whether you are being onboarded into space that is already committed to someone else.
An operator who says capacity is unlimited is telling you they have not thought about it.
The clause nobody reads
20. How you get your inventory back
This is the single most important question on the list, and almost nobody asks it during a sales call.
Ask: if I want to leave, how many business days until my inventory is picked, packed, and on a truck? Is there an exit or project fee? Who pays for the outbound freight? And can you refuse to release my goods over a disputed invoice?
That last part deserves attention. In the United States a warehouse generally has a statutory lien on goods in its possession for unpaid storage and handling charges, and most warehouse terms restate and broaden it. "They can't legally hold my inventory" is usually wrong. What you can do is read the lien language before you sign, understand what triggers it, and know whether a good-faith dispute over one invoice can freeze an entire quarter of stock.
Have a lawyer look at that paragraph specifically. It is the cheapest legal review you will ever buy.
Red flags that should end the conversation
No certificate of insurance, or one that names an entity you have never heard of
No written receiving SLA, or an SLA with no consequence attached
A per-unit price they will not itemize
Refusal to provide two current client references at roughly your volume
A liability cap tied to handling fees, presented as though it were coverage
Vagueness about exit terms, outbound freight, or the lien clause
Pressure to sign before you have seen the full agreement
How to score the answers
Do not weight all twenty equally. Insurance, the receiving SLA, the discrepancy protocol, the liability cap, and the exit terms are the five that determine what happens on your worst day. Get those in writing. The rest you can renegotiate later without much pain.
And call the references. Ask them one question that cuts through everything: what is the worst thing that has happened with this prep center, and how did they handle it? Any operator that has been running for two years has a story. The useful signal is whether the reference knows how it was resolved.
Where to start looking
If you are still building a shortlist, browse prep centers and warehouses by the services and locations you actually need, then bring this checklist to the first call. The operators worth working with will not mind the questions. Most of them wish more sellers asked.
For context on why this became urgent, see our guide on what changed when Amazon ended its FBA prep services.
