The most common e-invoicing errors

1. Wrong Peppol ID of the other party

Slovak entities are addressed with the scheme 0245 and the DIČ (tax ID), e.g. 0245:2121358349. Common mistakes: confusing the DIČ with the IČO or the IČ DPH, spaces, a missing scheme prefix. Check that you have the exact DIČ and the correct format. In our portal and in the check tool it is enough to enter the IČ DPH or the DIČ, we convert it to the correct format for you; this warning concerns mainly your own integrations. If an invoice ended up undelivered because of a wrong Peppol ID, correct the identifier and send the same invoice again with the same number and date, via the API with the same Idempotency-Key.

2. The other party is not registered in the SMP

An invoice can be delivered only to someone registered in the network (with a record in the SMP). If the partner does not yet have a provider, delivery fails; it is not an error in your invoice. Before the first sending, check that the recipient is reachable (for free in our check tool); many are only joining ahead of the 2027 mandate. What to do when a document ends with the error “not registered in the Peppol Network” is described in the article the customer is not in the Peppol network.

3. Wrong or incomplete VAT breakdown

The VAT breakdown must add up: every rate needs the correct category (S/Z/E/AE…) and percentage, and the totals must agree mathematically. Pay particular attention to reverse charge (AE) and exempt supplies (E): they must not be reported as standard (S). The format details are in the article on BIS Billing 3.0.

4. You send a PDF instead of a structured document

An e-invoice under the mandate is not a PDF attached to an e-mail. It must be a structured UBL document transferred through the network. You can generate a PDF for reading at any time, but the legally relevant one is the structured document.

5. Missing mandatory fields

Without the mandatory fields (number, date, document type, identification of the parties, currency, totals) the invoice is rejected by the network’s automatic check (the so-called Schematron rules). The solution: validate before sending (for free in our validator) and use software that enforces the mandatory fields. If our check stops an invoice before it is handed to the network, it is neither delivered nor reported to the Financial Administration: correct it and send it again, by all means under the same number (via the API with the same Idempotency-Key). If you send it on another day, the date of issue should be the day of the actual sending (FS FAQ, part I, question 74).

6. Forgotten tax reporting

From 2027 an invoice also comes with a report of its data to the Financial Administration. If the provider does not do this automatically, you risk not fulfilling the obligation. Check it: see data reporting (TDD) and the checklist for choosing a provider.

How to make it easier

You avoid most errors with good software or a good provider that validates before sending, handles the reporting automatically and has understandable error messages. You can try receiving invoices with us for free until 31 December 2026, before the mandate.