Why should EDI operators never change data on e-invoices?

We as an EDI operator sometimes receive requests from our customers to change data on electronic invoices. For example, “perhaps you could convert supplier product codes into buyer product codes”. Or “would you please change the units on invoice from trade units to transport units”. Of course we could, but we shouldn’t. Why?

e-invoice as a legal document

In the European Union (including all Baltic countries), e-invoices are considered legally acceptable only if they are the same both on sender’s side and receiver’s side. Requesting to change or modify an e-invoice might be caused by a misconception that e-invoices are not “real” invoices and could be modified by an intermediary. 

However, the key principles of the law are that the invoice issuing party should ensure the integrity of the content (no changes to content) of VAT invoices throughout the document storage period. So changing an e-invoice is against the law!

Product code conversion

Another common request is to change product codes while the document is in transit from sender to receiver. 

In order to convert product codes, the service provider should have the master data needed for this operation. For example, to convert the supplier codes on the document to buyer codes, first a mapping table for all supplier codes should be created in the service provider’s system. For each supplier code, a matching buyer code should be specified. 

And not just once, this mapping table should be updated for every new product or any change in the old ones. For each buyer (as most suppliers sell to multiple buyers, not just one). This could mean hundreds of thousands of codes to be kept in the service provider’s database.

This is not what EDI operators do. Instead, they transport documents securely in the right format to the right recipients. 

In general, using buyer product codes to refer to products is not the best practice at all. Supplier codes are much better. They stay the same for each product, as there is just one supplier of each individual product, while there can be thousands of buyers for that product. And the best practice is of course to use GTIN-s, the Global Trade Item Numbers, as these uniquely and explicitly identify each product, making it possible to avoid the need for mapping. Also, they minimize the probability of errors. Read more about GTINs here.

Product unit conversion

A third request customers sometimes make is to convert product units. Again, for this to be possible, a master data table needs to be set up at the service provider’s system. If the question is substituting trade units with logistics units, this data needs to be forwarded to the EDI operator for each and every product. 

And this information needs to be updated if anything changes at the supplier side. Or when there are new products launched, then their packaging data should also be sent to the EDI operator. 

Creating and maintaining a duplicating product units conversion system at an EDI operator is not a rational nor cost-efficient idea.  

In general, the best practice is to store and manage product data in suppliers’ ERP. In case your ERP is not very advanced in product data management, you should consider acquiring a special Product Information Management (PIM) system.