Peppol Invoice Response and MLR codes explained
After a Peppol invoice is delivered, the buyer can answer with an Invoice Response: a status such as RE (rejected) or UQ (under query), plus any reason codes such as REF or LEG and action codes such as NIN. The receiving side can also send a Message Level Response when the file itself failed validation, with codes such as RE, BV or SV and the rule that failed. Find your code below to see what it means and what to do. The codes come from OpenPeppol's Invoice Response transaction 3.1 and Message Level Response 3.0 and their code lists; Klarbon explains them in its own words.
In short
What Peppol response codes such as RE, UQ or CA, reasons such as REF or LEG, and validation codes such as BV or SV mean, and what to do next.
This list covers 34 codes from the official documents below. 14 have their own page; 20 are explained in the table only, as they are system or transport statuses with no fix in the invoice.
Invoice Response statuses
| Code | What it means |
|---|---|
| AB | Message acknowledged Peppol status AB in an Invoice Response means the buyer has received a readable invoice that can be understood and passed on for processing. Nothing to do. The buyer may send later responses about approval and payment. |
| IP | In process Peppol status IP in an Invoice Response means processing of the invoice has started in the buyer's system. Nothing to do. |
| UQ | Under query |
| CA | Conditionally accepted |
| RE | Invoice rejected |
| AP | Accepted Peppol status AP in an Invoice Response means the buyer has given final approval of the invoice and the next step is payment. Nothing to do. |
| PD | Paid Peppol status PD in an Invoice Response means the buyer has started payment of the invoice. With the reason PPD, the payment is partial. Nothing to do if the payment is as expected. If PPD shows a partial payment you did not expect, ask the buyer about it. |
Reasons for a status
| Code | What it means |
|---|---|
| NON | No issue Peppol reason NON in an Invoice Response means the buyer sends the response only to update the status, with no problem in processing the invoice. Nothing to do. |
| REF | References incorrect |
| LEG | Legal information incorrect |
| REC | Receiver unknown |
| QUA | Item quality insufficient Peppol reason QUA in an Invoice Response means the quality of what was delivered is not acceptable or not correct. Ask the buyer which quality issue they found and agree how to resolve the complaint. |
| DEL | Delivery issues Peppol reason DEL in an Invoice Response means the delivery proposed or made is not acceptable. Read the response details and ask the buyer what needs to change about the delivery. |
| PRI | Prices incorrect |
| QTY | Quantity incorrect |
| ITM | Items incorrect |
| PAY | Payment terms incorrect |
| UNR | Not recognised Peppol reason UNR in an Invoice Response means the buyer does not recognise the commercial transaction. Check with the buyer which purchase the invoice is for. |
| FIN | Finance terms incorrect |
| PPD | Partially paid Peppol reason PPD in an Invoice Response means the invoice has been paid partly, not in full. If you did not expect a partial payment, check the response explanation and contact the buyer. |
| OTH | Other reason Peppol reason OTH in an Invoice Response means the reason for the status is not one of the coded ones. Read the text, or ask the buyer. |
Actions the buyer asks for
| Code | What it means |
|---|---|
| NOA | No action required Peppol action NOA in an Invoice Response means the buyer asks for no action. Nothing to do. |
| PIN | Provide information Peppol action PIN in an Invoice Response means the buyer asks for missing information without a new invoice. Send the buyer the information they ask for without issuing a new invoice. |
| NIN | Issue a new invoice Peppol action NIN in an Invoice Response means the buyer asks for a corrected invoice to be issued again. Correct the invoice as instructed in the response, then issue and send it again. |
| CNF | Credit in full Peppol action CNF in an Invoice Response means the buyer asks for the invoice to be cancelled in full with a credit note. Issue a credit note for the whole invoice. |
| CNP | Credit in part Peppol action CNP in an Invoice Response means the buyer asks for a partial credit note for corrections only. Issue a credit note for the part to correct. |
| CNA | Credit the amount paid Peppol action CNA in an Invoice Response means the buyer asks for the amount paid on the invoice to be repaid. Repay the amount. |
| OTH | Other action Peppol action OTH in an Invoice Response means the action the buyer asks for is not one of the coded ones. Read the text, or ask the buyer. |
Message Level Response codes
| Code | What it means |
|---|---|
| AB | Message acknowledged (MLR) Peppol AB in a Message Level Response means the receiving side acknowledges receipt of the document without confirming that it has passed validation. Nothing to do. |
| AP | Message accepted (MLR) Peppol AP in a Message Level Response means the received document was accepted after validation. Nothing to do. |
| RE | Message rejected (MLR) |
| SV | Syntax violation |
| BV | Business rule violation, fatal |
| BW | Business rule warning Peppol line status BW in a Message Level Response means the document breaks a business rule that is flagged as a warning, not as fatal. Check the warning description and correct the invoice where it applies. Check the overall response code: AB acknowledges receipt, AP means accepted and RE means rejected. |
Read the official document
- Peppol BIS Invoice Response 3.1 (BIS 63A), with its code lists Source: Peppol BIS Invoice Response 3.1 (BIS 63A), with its code lists, version Peppol BIS 3, 2026-Q2 release, published by OpenPeppol AISBL, read on 8 November 2026.
- Peppol BIS Message Level Response 3.0 (BIS 36A), with its code lists Source: Peppol BIS Message Level Response 3.0 (BIS 36A), with its code lists, version Peppol BIS 3, 2026-Q2 release, published by OpenPeppol AISBL, read on 8 November 2026.
Klarbon explains each code in its own words; the official wording is in the document linked above.
Frequently asked questions
What is the difference between an Invoice Response and a Message Level Response?
A Message Level Response can acknowledge receipt without validation (AB), report acceptance after validation (AP) or report rejection with details of the errors (RE). An Invoice Response comes from the buyer and reports where the invoice stands in their approval and payment process.
Why does the same code appear twice?
AB, AP and RE are used both in an Invoice Response and in a Message Level Response, with different meanings, and OTH is both a reason and an action. Check which message your software shows.
Can the buyer change a status later?
Statuses advance in a fixed order, AB, IP, UQ, CA, RE, AP and PD, but stages can be skipped and UQ can be repeated. RE and PD without PPD are final; PD with PPD reports partial payment and is not final. Changes outside this sequence must be handled manually between you and the buyer, not through another Invoice Response.
Where do the codes come from?
From OpenPeppol's Invoice Response transaction 3.1 and Message Level Response 3.0 and their code lists, on docs.peppol.eu, read on 8 November 2026. Klarbon explains each code in its own words and links to the source.