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How Item Data Drives Amazon POs and Prevents Shortages

Learn how Amazon uses your item data to generate purchase orders—and how reviewing that data helps prevent costly shortages.

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Written by Support
Updated over 2 weeks ago

How Item Data Powers Amazon POs

Each Product Has Key Data in Amazon’s Catalog Amazon pulls important attributes from your Vendor System Data during Item Setup. Each Consumer-Level Sellable Product is treated as a distinct item, even if it’s part of a multi-pack. This data becomes the foundation for Purchase Orders, inventory tracking, and payment accuracy.

How Key Item Data Flows Into Amazon’s Catalog

Key Attributes Pulled During Item Setup

Amazon uses these core attributes from your system to set up and track each product in the catalog. Getting them right is critical for clean POs, payments, and listings.

  1. ASIN #. Every product configuration gets a unique Amazon Standard Identification Number (ASIN). This is assigned during item setup.

    i.e. ASIN B00987DCBA

  2. External ID. Each item must also have a unique external ID, like a UPC, EAN, or GTIN. Amazon scans this ID to identify the product.

    i.e. 123456789012
    ​

  3. Vendor SKU #. A unique identifier you assign to the product. It can be anything (UPC, internal code, ASIN), but it should stay consistent for each product version. Matching your External ID is recommended.
    ​i.e. 123456789012
    ​

  4. Model #. Also vendor-defined, the Model # often represents the design or style. If the item is the same, it can repeat across sizes or packs.
    ​i.e. MLK-001
    ​

  5. Case Quantity. This defines how many sellable units are in one case.

    i.e. 1

  6. Unit Cost. This is the price Amazon pays per item.

    i.e. $1.00

  7. Case Cost. Amazon calculates this using Case Quantity × Unit Cost.

    i.e. $3.00

From Amazon’s Catalog to Purchase Orders

Once your item data is set up in Amazon’s catalog, it powers the systems that generate your Purchase Orders (POs). That means your catalog setup directly influences how and what Amazon orders from you.

Two key catalog configurations at the vendor code level impact your POs:

1. Unit of Measure (UOM). This defines how Amazon orders your products—either by the unit (each sellable item) or the case (a group of units). The total product count doesn’t change, but the PO format and cost interpretation do.

Let’s say Amazon wants to order 18 individual milk cartons (or 6 total 3-packs).

Both total $18, but how they appear and how Amazon expects to receive and pay for them depends on the UOM. Even with perfect product delivery, a mismatch in this setup can cause shortages or chargebacks.

2. Item Identifier. Amazon uses an item identifier to match received products to its catalog. If this identifier doesn’t align with your setup, Amazon may treat the item as incorrect or missing—leading to shortages or claim rejections. By default, Amazon uses the External ID (UPC, EAN, or GTIN) to identify items. However, using your Vendor SKU is more reliable. You can check what you’re currently using by comparing the PO SKU value to your catalog's Vendor SKU and External ID fields in Vendor Central.

How to Switch to Vendor SKU Setup

This recommended setup helps prevent mismatches, chargebacks, and shortages. It also gives you more control by using your internal SKU system instead of relying on Amazon’s default External ID.

  1. Make sure all ASINs in your catalog have accurate Vendor SKU values.

  2. Submit a case in Vendor Central:

    1. Go to Support —> Contact Us —> Manage My Catalog —> Item Detail Edit —> Still Need Help —> Send Email

    2. Include: A brief description and the vendor code

Preventing Amazon Shortages Through PO Review

Catalog Errors Can Lead to Shortages

Every PO Amazon generates pulls from the product data in your catalog after item setup. That means if there's a data error input — like the wrong case quantity, unit cost, or item identifier — it shows up on the PO and can result in shortages.

Common Catalog Issues That Cause Shortages

Unit of Measure (UOM) Mismatch Across Process

When the same item is interpreted as "each" vs. "case" at different points, it creates discrepancies between what Amazon thinks it ordered and what you shipped.

i.e. 18 Cartons —> 18 Cartons —> 6 Cases (Of 3 Cartons) —> 6 Cases (Of 3 Cartons)

If Amazon expected 18 individual cartons, but your ASN says 6 cases of 3, it can be flagged as a shortage—even if the shipment is correct.

Item Identifier Mismatch Across Process

If the item identifier used to match your product in Amazon’s system isn’t aligned across your catalog, PO, and invoice, the product may not reconcile properly.

i.e. 123456789012 —> 123456789012 —> 123-MLK-CA —> 123-MLK-CA

If Amazon’s catalog expects a UPC but the invoice only references your internal SKU, it can cause a mismatch—even if it’s the same product.

How to Review POs to Prevent Shortages

This is a recommended weekly check-in to catch mismatches before they cause shortages. When Amazon places a PO, it’s based on the data in their catalog—not necessarily what’s in your internal system. The PO Review Process helps you proactively compare those two sources and flag any mismatches before they result in shortages.

1. Export Recent POs

  1. In Vendor Central, go to Orders —> Purchase Orders —> Manage POs

  2. Filter by “Vendor Code” and “Order Date” —> “Apply”

  3. Select all relevant POs

  4. Click “Open selected POs”

  5. Click “Export PO to Excel”

This file shows how Amazon has the product data stored today.

2. Compare to Your Master Data

After exporting, you'll have two files: your internal master data and Amazon’s PO data. For each ASIN, compare the following key attributes:

Case Quantity: Flag if the number of units per case doesn’t match your master data. To correct:

  1. Go to: Manage Case Log—> Create New Issue —> Purchase Orders —> Case Pack Quantity Update

  2. Include: A brief description, the vendor code, PO & ASIN, and the correct case quantity

  3. Submit!

Unit or Case Cost: Flag if the cost per item or case is off. To correct:

  1. Go to: Manage Case Log —> Create New Issue —> Manage My Catalog —> Cost Price Inquiries —> Still Need Help

  2. Include: A brief description, the vendor code, PO & ASIN, and the correct selling unit cost

  3. Submit!

Unit of Measure (UOM): Flag if Amazon ordered by “case” but you ship “each” or vice versa. To correct:

  1. Go to: Manage Case Log —> Create New Issue —> Purchase Orders —> Purchase Order Management —> Still Need Help

  2. Include: A brief description, the vendor code, impacted PO’s, and the correct UOM

  3. Submit!

ASIN-to-Item Identifier Relationship: Flag if the SKU field in Amazon’s PO does not match the expected Item Identifier from your system. To correct:

  1. Go to: Manage Case Log —> Create New Issue —> Manage My Catalog —> Item ID Update —> Still Need Help

  2. Include: A brief description, the vendor code, ASIN, and the correct item identifier

  3. Submit!

ASIN-to-External ID Relationship: Flag if the same External ID (UPC/EAN/GTIN) is tied to multiple ASINs that represent different selling configurations (e.g., 1-pack and 6-pack).

  1. To identify duplicates, combine your Amazon PO data with your internal master file

    1. Select the “ASIN” and “External ID” columns and use Remove Duplicates to clean up the list.

    2. Insert a Pivot Table with

      1. Rows: External ID

      2. Values: Count of ASIN

    3. Filter to show External IDs with a count greater than 1

    4. Review those duplicates to determine if the ASINs represent different selling configurations

      1. If they do, the mapping is valid

      2. If not, the ASINs likely need to be corrected

  2. To correct the issue(s), submit a case to Amazon

    1. Go to: Manage Case Log —> Create New Issue —> Manage My Catalog —> Item ID Update —> Still Need Help

    2. Include: A brief description, the vendor code, impacted ASIN’s, and the correct External IDs for each configuration

    3. Click Submit!

Catalog Error Shortages

When Amazon receives your product, it expects everything to match the data in its system. If something’s off—a mislabeled unit of measure, the wrong cost, or a mismatched item identifier—Amazon might:

  • Pay you for fewer units than you shipped

  • Short-pay your invoices due to receiving discrepancies

  • Delay payment or even reject claims due to catalog mismatches

Shortages aren’t always about missing product. More often, they’re caused by mismatched data across systems. That means money left on the table, and it adds up.

The PO Review Process Helps Prevent RevLoss

Shortages can quietly chip away at your margins. Even when your product is perfect and delivered on time, catalog mismatches can result in Amazon paying you less or delaying your delivery.

A weekly PO Review allows you to catch those mismatches before they cause deductions, rejections, or payment delays. The sooner you catch issues, the faster you can submit corrections and protect your revenue.

It’s not just about fixing errors—it’s about staying ahead of them.

Need more support?

Reach out to your SupplyPike Customer Success Manager. We’re here to help you get paid and get better.

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