Mandatory e-invoicing in Slovakia: what a digital postman needs to do and how invoice delivery works

From January 1, 2027, Slovak companies will be under a mandatory e-invoicing regime and will be required to issue and receive invoices in a structured electronic format. Delivery will be handled by a certified delivery service provider, known as a digital postman, via the Peppol network.

However, many practical questions remain unanswered. How will the digital postman work in practice? How do you verify if a recipient is available on the Peppol network? What happens if an e-invoice cannot be delivered or if there is a technical outage?

In this article, we summarize the key information regarding how the digital postman and e-invoice delivery work. We also answer the most frequent questions raised during Financial Administration seminars that accounting departments will need to address in relation to mandatory e-invoicing.

One Tax ID, one digital postman for receiving e-invoices

For receiving e-invoices, one Tax ID should be linked to one digital postman. A company does not need a separate solution for every supplier or customer. The Peppol network ensures that the invoice travels from the sender's provider to the recipient's provider.

The situation can be more complex for outgoing invoices. A company might use multiple digital postmen, for example, if invoices are generated in different accounting, ERP, or other enterprise systems. From the perspective of the accounting department, it is therefore not enough to simply decide who the digital postman will be. It is also necessary to have clarity on which system individual invoices are sent from and where information about their processing is returned. For larger companies, this is where e-invoicing integrates with the setup of existing accounting processes.

Is the recipient on the Peppol network? The system should check this before sending

Before sending an e-invoice, it is necessary to verify whether the recipient is registered on the Peppol network. The accounting system or digital postman should query the Peppol directory; registration can also be verified manually in the Peppol Directory by company name or tax identifier.

However, with a high volume of documents, an accountant should not have to perform this check manually for every invoice. The e-invoicing solution should verify the recipient automatically and flag any potential issues before sending.

Equally important is the information that is returned to the accounting system afterward. A status of "sent" alone is not enough. The accountant needs to know whether the recipient was found, whether the e-invoice passed validation, and whether it was successfully delivered.

What if the recipient cannot accept an e-invoice?

The digital postman should return a delivery confirmation to the sender, indicating whether the recipient was found in the network. According to the Financial Administration, the sender fulfills their legal obligation by handing the e-invoice to the digital postman and notifying the Financial Administration of the required data. However, if the invoice cannot be delivered via the network, it remains necessary to ensure delivery to the recipient by another agreed-upon method so that they can process and pay the document.

It is therefore important for accountants that the solution separates the actual sending of the e-invoice from the delivery result and makes it possible to track the status of a specific document.

Digital postman outages must be traceable

Another possible situation is a technical failure on the part of the company, the digital postman, or the delivery infrastructure itself.

The system should alert you to the failure, and the e-invoice should be sent at the earliest possible opportunity. It was also stated at Financial Administration seminars that if a company can document an objective technical cause, it should not be sanctioned for such a delay. When assessing the situation, a distinction should be made as to whether the problem originated with the company, the delivery service provider, or the network.

This increases the importance of status history and error logs. The accounting department should be able to retrospectively determine when an e-invoice was prepared for sending, whether a technical error occurred, and when it was subsequently sent successfully.

For larger companies, e-invoicing should be integrated with the accounting system or ERP

With a small number of documents, working directly in the digital postman's interface may be sufficient. However, as the volume of invoices grows, integration with an accounting system or ERP becomes an important part of the overall e-invoicing solution.

Integration is what determines whether an accountant will have to work in multiple environments and manually check the status of individual documents, or whether received e-invoices, validation results, and delivery information will automatically sync with the system they use daily.

When choosing a digital postman, it therefore makes sense to verify not only Peppol support but also the method of integration with the accounting system, handling of status information, recipient verification, and error resolution.

These are the areas that will have the greatest impact on the daily processing of e-invoices in the accounting department starting in 2027.

See how e-invoicing can work in your system

On the page e-invoicing solution from GRiT you will learn how GRiT acts as a secure digital postman, how it integrates with enterprise systems, and how it handles e-invoice processing. Thanks to our experience with e-invoicing in international markets, we help companies prepare for new requirements practically and without unnecessary complications.

Try our e-invoicing DEMO to see how sending, receiving, and checking the status of an e-invoice works in practice.