The most common mistakes and misconceptions when moving to e-invoicing
Most e-invoicing problems do not come from the technology. They come from misconceptions about what the law actually requires. These are the ones we see most often — together with the right way to handle each of them.
Misconception 1: “I email PDFs, so I already invoice electronically”
A PDF attached to an email is not an electronic invoice. From 1 January 2027 the law — Act No. 385/2025 Coll. (zákon č. 385/2025 Z. z.) — requires structured XML compliant with EN 16931 (UBL syntax), delivered through a delivery service. A document that does not meet those requirements is not treated as an e-invoice: the data never reaches the Slovak Financial Administration and the obligation is not discharged.
Misconception 2: “I have to send my proforma invoices over Peppol”
You do not — and, in fact, you cannot. A proforma invoice (a request for payment) does not carry the particulars of an invoice under the VAT Act, is not a tax document and is not sent through the e-invoicing system. Do watch the moment the payment arrives, though: once the advance payment lands, an invoice for the payment received has to be issued under Section 72(1) — and that one does go out electronically.
Misconception 3: “I will keep issuing summary invoices exactly as I do now”
From 1 January 2027 a summary electronic invoice may cover a period of no more than one calendar month (Section 85o(7)). A summary invoice under Section 75 covering a longer period no longer applies in the domestic electronic regime. Under lease agreements with an agreed payment schedule, an e-invoice is issued for each recurring lease service.
Misconception 4: “I will reject a faulty invoice through Peppol”
The Peppol network has no statutory mechanism for rejecting an invoice you have received. The procedure is the same as with a paper invoice: you settle the discrepancy bilaterally with your trading partner — by agreeing a correction, a credit note or a new corrected invoice. Errors found after sending are resolved with corrective documents, never by editing the original.
Misconception 5: “I am not VAT-registered, so none of this concerns me”
A non-VAT payer does not have to issue e-invoices, but does have to be able to receive them — as does every legal entity and every business that is a taxable person (including the liberal professions and landlords letting property). Without a registration for receiving, a VAT payer will send you an invoice through a delivery service and will have discharged their obligation — and you will be left without the document.
Misconception 6: “EDIFACT — my old EDI channel — is good enough”
From 1 January 2027 EDIFACT does not meet the definition of an electronic invoice for VAT purposes in domestic transactions. The exchange itself may carry on, but XML compliant with EN 16931 has to be produced from the invoicing data (the CEN/TS 16931-3-4:2017 mapping) and the reporting obligation has to be met — automatically, if you invoice through a certified e-invoicing provider.
Misconception 7: “I will keep an eye on the reporting deadlines myself”
Data from an invoice you issue is reported when the invoice is issued; data from an invoice you receive, within 5 days. Tracking those deadlines by hand is a needless risk of a fine of up to €10,000 (up to €100,000 for repeated breaches) — invoice through a certified e-invoicing provider and the reporting runs automatically, and the statutory exemption from liability also covers a demonstrable failure on the provider's side.
Tip
All seven misconceptions are answered by a single decision: invoice through a certified e-invoicing provider that takes care of the format, the delivery and the reporting for you. eFaktúra (EFSK000028) already does exactly that — and in 2026 it is free.
Frequently asked questions
No. Not even an electronically signed PDF is structured XML compliant with EN 16931, so it does not meet the definition of an electronic invoice from 1 January 2027.
With a corrective document — a credit note or a new corrected invoice agreed with your partner. The original that was sent is never edited, and Peppol does not deal with invoice rejection.
No. From 1 January 2027 a summary electronic invoice may cover supplies over no more than one calendar month.
Sources
Sort out your e-invoicing today
Electronic invoicing becomes mandatory in 2027. Find out how to prepare and whether it applies to you.