In this article, learn about:
- What an order management system does with an order, and what it never touches
- How an order management system, an ERP, and a warehouse system divide the work
- Which system answers a retailer’s purchase order, ship notice, and invoice
- When a growing supplier actually needs an order management system, with more supplier guides at The Supply Chain Source
Most explanations of the order management system (OMS) are written for a brand that ships parcels to shoppers. A supplier selling into Walmart, Target, or Home Depot has no cart or carrier in the middle of the transaction. The order arrives as a structured file from the retailer, and the retailer expects several structured files back on a schedule it sets. The definition of an order management system therefore matters less than its boundary, which is what this article covers.
What Is an Order Management System?
An order management system is software that manages order data. It takes in orders from every channel a company sells through, checks them for problems, decides which inventory should fill them, and tracks them until the goods arrive. Four jobs sit inside that description:
- Capture: receiving orders from wholesale accounts, marketplaces, and direct channels in one place
- Validation: checking an order against pricing, quantities, and business rules before anyone acts on it
- Allocation: deciding which inventory, in which location, is promised to which order
- Status: tracking where each order stands, so anyone can answer a customer question
What an order management system does not do is as important: it does not pick, pack, or ship anything; it does not post revenue to the general ledger or decide what should happen to an order and communicate that with other systems.
OMS vs ERP vs WMS: Who Owns What?
Three systems touch an order, and each owns a different part of it. An enterprise resource planning system (ERP) runs the business record. A warehouse management system (WMS) runs the building. The OMS sits between them and runs the order.
System | Core job | What it decides | What it does not do |
Order management system | Manages the order across channels | Whether an order can be promised, split, backordered, or allocated | Move stock, post financials |
ERP | Manages the business record | Costing, purchasing, payables, revenue recognition | Multi-channel order intake, order-level validation |
Warehouse management system | Manages the physical work | Where to pick, how to pack, what goes on the truck | Accept or reject an order, invoice it |
Inventory appears in all three, which is the usual source of confusion. The ERP holds inventory for valuation and purchasing. The OMS reads available inventory to decide what it can promise. The WMS tracks inventory by bin, carton, and pallet so someone can find it.
No standards body publishes this division. It is industry convention, and vendors draw the lines differently. Most ERP systems include order entry, and many suppliers run for years on that alone.
Which System Answers the Retailer’s Purchase Order?
For a supplier, this question decides everything else. Retail orders arrive through electronic data interchange (EDI), a standard format that lets two companies exchange business documents without anyone retyping them. The formats are maintained by X12, an ANSI-accredited standards organization that has developed EDI standards for more than 40 years.
The Documents a Retailer Expects Back
The sequence is short, and each document has one job:
EDI 850, the purchase order (PO). The retailer sends what it wants to buy, in what quantity, at what price, to which location, by which date. X12 describes the purchase order process as establishing the legal contract between buyer and seller.
EDI 997, the functional acknowledgment. The supplier’s system reports that the file arrived and passed formatting checks. It says nothing about whether the order can be filled.
EDI 855, the purchase order acknowledgment. The supplier reports what it can actually ship, including shortages and substitutions. X12 describes the 855 as reporting back from the seller’s PO system after the 850 has been processed.
EDI 856, the advance ship notice (ASN). Before the truck leaves, the supplier sends what is on it: carrier, tracking, pallet and carton detail, barcodes, and expected arrival. X12 calls this the transaction that ties the order to the delivery process.
EDI 810, the invoice. After the goods ship, the supplier asks to be paid, referencing both the order and the shipment.
Where Each Document Actually Comes From
Those five documents do not all come from one system. The 855 comes from wherever order data lives. The 856 usually comes from wherever shipping data lives, which is often the warehouse system rather than the order system. In one worked supplier example, the WMS generates the ASN while the accounting system generates the invoice.while the accounting system generates the invoice.
That is why “do I need an order management system” is the wrong first question. The better one is whether every document in the sequence has a system responsible for producing it, correctly, on the retailer’s clock.
Related Reading: EDI 856: Advance Ship Notice/Manifest
Does an Order Management System Handle EDI?
The answer varies by system. Some order management systems read and write EDI documents directly. Others hand that work to a separate integration layer and only receive the translated order. Many ERP systems accept an order but can’t produce a compliant acknowledgment or ASN at all.
What EDI Order Management Actually Covers
EDI order management is a set of capabilities rather than a single product category. Because of that, suppliers evaluating software tend to ask about the documents rather than the category. Useful questions include:
- Which EDI documents does this system generate, and which does it only receive?
- Can it produce an 855 that reports a partial quantity, not just an approval?
- Does it build the 856 from actual carton and pallet data, or from the original order?
- When a retailer changes its requirements, who updates the mapping?
An answer of “we integrate with an EDI provider” is a real answer. It means the documents are somebody else’s job, and a supplier should know whose.
What Happens When the Documents Are Wrong or Late?
The cost shows up in payment, not in an error message on a screen. Retailers check the invoice against both the PO and the ASN, a check commonly called a three-way match. When the three documents disagree, even by a single case, payment is held until someone investigates.
The ASN carries the most operational weight, because retailers use it for receiving and labor planning. Late or inaccurate ship notices are one of the largest causes of chargebacks, and a missing ASN can lead a retailer’s system to reject an entire shipment at the dock. So the question is whether a supplier’s systems can build accurate documents without a person checking each one by hand.
Related Reading: EDI Chargebacks Explained
Do You Need an Order Management System Yet?
Many suppliers do not, at least not immediately. Suppliers early in a retail relationship often run on an ERP plus a web-based EDI service, where staff enter shipment details online and the service formats and sends the documents. Larger suppliers connect EDI software directly to their systems so documents move without manual work. Some use value-added networks, which pass documents securely between trading partners.
The pressure to buy an OMS usually arrives with a second or third channel. One retailer, one warehouse, and a few hundred orders a week can be managed inside an ERP. Add a marketplace and a direct channel, each with its own rules, and order data stops fitting in a system built for accounting.
One question sorts most of this out: which system would send an accurate ship notice tomorrow if a retailer added a new distribution center? A stack with a clear answer is working, and a stack without one has a gap worth closing before the next mandate.
Frequently Asked Questions
Is an order management system the same thing as an ERP?
No. An ERP runs the money and the business record. An order management system runs the orders and decides what can be promised. Most ERP systems include order entry, which is a smaller job.
Does a small supplier need an order management system to sell to a big retailer?
Not always. Retailers care about the documents, not the software you bought. A supplier that sends an accurate 855, 856, and 810 on time meets the rule. Those files can come from an ERP, an EDI service, or a dedicated order system.
Which retail document causes the most problems?
The advance ship notice. Retailers rely on it to plan receiving and staffing, and late or wrong notices are a leading cause of chargebacks.
Who generates the advance ship notice, the order system or the warehouse system?
It depends on the stack, and that is why the question matters. Shipping detail usually lives in the warehouse system, so the notice often starts there rather than in the order system.
Want To Go Deeper on What Your Retailer Expects?
It is worth working out which system owns which document before a retailer sets a deadline. SPS Commerce publishes free supplier education at The Supply Chain Source. You will find plain-language guides to each document in the order sequence.