Costco PO/Invoice Mismatch Chargeback: The 3-Way Match

Executive Summary & Quick Answer

Executive summary: Costco's payment flow depends on three EDI documents telling the same story — the 850 purchase order, the 856 ASN, and the 810 invoice. When the invoice disagrees with the PO or ASN on quantities, prices, or item identifiers, Costco deducts. Data mismatches across these documents are among the most common causes of Costco deductions, and they're also the most mechanically preventable: enforce a three-way match before the invoice leaves.

Quick answer: A Costco PO/invoice data mismatch chargeback is assessed when the 810 invoice doesn't align with the purchase order or ASN — wrong quantities, prices, or item identifiers. Data mismatches between the 850, 856, and 810 are among the most common Costco deductions, prevented by a three-way match before transmission.

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Deep Dive: What Triggers the Mismatch Chargeback

Costco reconciles the invoice against the order and the shipment. Three fields must agree across all three documents:

Field	850 (PO)	856 (ASN)	810 (Invoice)
Quantity	Ordered	Shipped	Billed
Price	PO cost	—	Billed cost
Item ID	Costco item # / GTIN	Shipped GTIN	Billed item

Any disagreement — invoice quantity ≠ shipped, invoice price ≠ PO, invoice item ID ≠ Costco's item file — is a mismatch Costco deducts against. The classic failure is invoicing from the PO before shipment corrections are reflected, so the 810 bills a reality that never left the dock.

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Business & Financial Impact

• Deduction ≈ 1–3% of PO value per mismatch incident (per the record).
• Common by frequency: data mismatches are among the top Costco deduction causes, so the rate matters as much as the per-incident cost.
• Cross-dock amplification: Costco's depot model has little tolerance for reconciliation friction — mismatches slow receiving and compound.
• Disputes rely on shipment evidence reconciled to the PO.

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Root Causes (Ranked)

1. Invoice quantities/prices differ from the PO — billed before corrections landed.
2. Item identifiers don't match Costco's item file — new-item setup or GTIN drift.
3. Invoice built from the PO, not the shipment — ignores short/over/substitution.
4. Price changes not synced to Costco's item file before invoicing.

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Step-by-Step Prevention Workflow

850 ─┐
856 ─┼─► three-way match BEFORE 810 transmit:
810 ─┘     ├─ qty: 810 == 856 shipped?
           ├─ price: 810 == 850 PO?
           └─ item ID: 810 == Costco item file?
                 │ any mismatch → block + fix → regenerate
                 ▼
              transmit

1. Three-way match 850 / 856 / 810 before transmission.
2. Invoice from confirmed shipped quantities at PO prices — never the raw PO.
3. Sync item identifiers with Costco's item file on every new-item setup.
4. Confirm price changes are loaded on Costco's side before billing new prices.

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Mismatch vs Quantity Discrepancy vs Late ASN

Code	What it is	Where it breaks
Invoice mismatch	810 disagrees with 850/856	Invoice data
Quantity discrepancy	Received ≠ ordered/invoiced	Physical count
Late/inaccurate ASN	856 late or wrong	Ship notice

Related: Quantity discrepancy · Late ASN · all Costco violations

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Supplier Checklist

• Three-way match (850/856/810) enforced before every invoice
• 810 billed from confirmed shipped quantities at PO prices
• Item identifiers synced with Costco's item file at setup
• Price changes confirmed loaded on Costco's side before billing

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FAQs

What is a Costco PO/invoice mismatch chargeback? A deduction assessed when the 810 invoice doesn't align with the purchase order or ASN — wrong quantities, prices, or item identifiers.

How much does it cost? Roughly 1–3% of PO value per mismatch incident, and because mismatches are common, the frequency compounds the cost.

Which EDI documents are involved? The 850 (PO), 856 (ASN), and 810 (invoice). The chargeback is the 810 disagreeing with the 850 or 856.

How do I prevent invoice mismatches? Enforce a three-way match before transmission, invoice from shipped quantities at PO prices, and keep item identifiers synced with Costco's item file.

Why do mismatches happen even when goods ship correctly? Usually the invoice is built from the PO before shipment corrections (short/over/substitution) are reflected, so it bills a reality that didn't ship.

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