# What an e-invoice is — and is not

URL: https://postman.slovakodata.com/help/en/povinnosti/co-je-efaktura/
Updated: 2026-07-25

Why a PDF is not enough, which documents travel over the network, and how e-invoices must be archived.

The most common misunderstanding in this whole area sounds like this: "but
we have been sending invoices electronically for years". An electronic
invoice in the legal sense is something different from an invoice sent
electronically.

### A PDF is not an e-invoice

An electronic invoice is a **structured XML document** following the European
standard EN 16931 in one of the permitted syntaxes — **UBL 2.1 or CII**. An
accounting system can read and process it on its own, without anyone retyping
the data.

In the Peppol network the Peppol BIS Billing 3.0 profile is used in practice,
which is built on UBL; the law itself does not narrow it to a single syntax.

A PDF or a scanned document does not meet that condition — those are images.
A human can read them; a machine cannot.

The **EDIFACT** format also stops meeting the definition of an electronic
invoice for domestic transactions from 1 January 2027. If you use it, the
data must be converted to XML per EN 16931 in UBL or CII syntax. The mapping
is described in CEN/TS 16931-3-4:2017.

### Which documents travel over the network

The eFaktúra system carries documents that qualify as invoices under § 72 of
the VAT Act:

- **invoices**,
- **self-billing invoices** — the buyer issues the invoice on the supplier's
  behalf,
- **credit notes**.

### Which do not

A **proforma invoice or a request for payment** is not an invoice under the
VAT Act — issuing it creates no tax liability and it is not sent over the
network.

Note the distinction: if you **receive a payment before the supply** of goods
or services, an invoice for that payment must be issued under § 72(1). Such
a document does qualify as a tax document and must go over the network.

**Rent and payment schedules.** From 1 January 2027 a summary invoice under
§ 75(2) covering an agreement on rent payments can no longer be used for
domestic e-invoicing. The taxable person must issue an electronic invoice for
each recurring rental service supplied.

### Summary invoices

A summary electronic invoice covering several separate supplies is possible,
but only for a period of at most one calendar month (§ 85o(7)).

### Corrections

An invoice sent into the network cannot be withdrawn. The usual correction
path is the same as on paper:

1. issue a **credit note** against the original invoice,
2. send a new, correct invoice.

The alternative is a corrective invoice, which must satisfy all Peppol BIS
Billing 3.0 requirements and carry an unambiguous reference to the original
invoice in the `BT-25` field.

Rejection of an invoice is **not** sent over Peppol — the law introduces no
such obligation. Discrepancies are resolved directly with the trading
partner, exactly as with a paper invoice.

### Archiving

The taxable person must retain the electronic invoice for **ten years** from
the end of the calendar year it relates to (§ 85o(15)). It must be kept **in
XML format** — in the form in which it was issued and delivered, not as a
printed or converted document.

### Source

Financial Directorate of the Slovak Republic, **9/DPH/2025/IM — Frequently
asked questions on eInvoicing**; Act No. 222/2004 Coll. on VAT as amended by
Act No. 385/2025 Coll.