The EDI standard has more to say about deductions than most suppliers realise. The problem is rarely that the standard is missing a piece. It is that your trading partner decides which pieces are in play, and that decision changes how much work every deduction becomes.
The document built for this is the 891
There is a transaction set designed specifically for asking about a deduction. It is the 891, the Deduction Research Report.
It works in both directions. A seller uses it to request information about a deduction taken from an invoice, and the buyer or the buyer's agent uses it to supply the detail needed to resolve the amount. That is exactly the conversation a supplier wants to have when money goes missing from a payment.
Whether your partners support it is a different question entirely. We went looking for trading partners publishing an implementation guide for the 891 and did not find one. That is not proof that nobody uses it, and the 891 sits in the same family as the grocery documents that plenty of partners do use. But it does mean the honest answer is to ask your partner rather than assume the document is available to you.
The 812 is the adjustment itself
The 812 is the Credit/Debit Adjustment, the electronic version of the credit or debit memo that has been in accounts payable forever.
It is not only a notification. It can tell a trading partner that an adjustment or billback has happened, and it can be used to request one. Either side can send it, and it references the invoice or purchase order it relates to while carrying line detail: which item, how many, and why.
On paper, then, it is a conversation.
In practice, with the retailers doing the deducting, it tends to come one way. They issue 812s to you. If you are waiting for the moment where you send one back and the matter gets discussed, that moment does not usually arrive, and it is worth knowing that before you build a process around it.
Still, when a deduction does arrive on an 812, it is the friendliest form it can take. You can line it up against what you actually shipped and invoiced and see whether the claim holds.
Many deductions never arrive on an 812
The other place deductions live is the 820, the Payment Order and Remittance Advice. That is the document telling you what the buyer paid and what came off before they paid it.
Two things about that matter.
The money has already moved. An 812 can arrive ahead of settlement. An 820 is the settlement, with the deduction already inside it.
And the detail is usually thinner. Often what you get is a deduction code and an amount, without the line-level context you would have wanted.
So the same deduction is a different job depending on which document carried it. On an 812 you are checking a claim. On an 820 you are rebuilding one, going back to your own invoice and ship notice to work out which shipment, which line, and which date the retailer is describing.
That rebuilding is slow, it is unpaid, and it is a large part of why deductions go undisputed far more often than they are genuinely correct.
The reason code is a claim, not a finding
Whichever document it rides on, the reason code is the retailer's account of what happened. It is the start of an investigation rather than the end of one.
We have gone through this in detail in one reason code, four root causes. A late ASN is the clearest case. The code says the notice was late, which can be perfectly true while the cause sits in any of four different places, only some of them yours.
Treating the code as a finding is how a supplier spends a year fixing the wrong thing.
The dispute happens somewhere that is not EDI
Even where the documents flow cleanly, the dispute itself usually leaves EDI altogether. At large retailers it goes through their own portal, against the specific deduction, following their submission rules.
Two consequences, both of which cost money when people meet them late.
Filing in the wrong place does not get redirected. A dispute raised somewhere other than the route the retailer specified can end up closed without anyone assessing it.
And there is no single clock. Dispute windows vary by retailer and, more importantly, by deduction type at the same retailer. The window for a general accounts payable query and the window for a compliance deduction are rarely close to each other, and the compliance ones tend to be both the shortest and the ones needing the most investigation.
Which means you cannot run one deduction process. You need to know which clock applies before the deduction lands, because working it out afterwards is how windows close.
What to ask before any of this matters
Four questions, all better asked during onboarding than during a dispute.
Which document carries your deductions? If it is the 812, keep them and match them against your invoices and ship notices as they arrive. If it is the 820, accept that you are in the rebuilding business and set yourself up for it.
Do you support the 891? Ask directly. If the answer is yes, you have a supported route for requesting detail. If it is no, you have learned something useful about how much evidence you will have to assemble yourself.
Where do disputes go, and in what format? Get the exact route and the exact submission rules.
How long do I have, by deduction type? Not one number for the retailer. A number for each category of deduction they raise.
None of this turns an invalid deduction into a valid one. It decides whether you find out in time to say so.
Send your deduction export. Root causes ranked by dollars, back in about 7 days. The first 5 audits are free.