E-invoicing from 1 January 2027: what exactly becomes mandatory
Slovakia has passed an amendment to the VAT act — Act No. 385/2025 Coll. on electronic invoicing and data reporting. From 1 January 2027, invoices between businesses stop being PDF attachments in email: they become structured electronic invoices (e-invoices), sent over the secure pan-European PEPPOL network. Here is the whole picture — clearly and without legal jargon.
What an e-invoice is (and what it is not)
An electronic invoice — e-invoice for short, also called a structured or digital invoice — is an invoice in the form of data that accounting software can read by itself, with no retyping. Picture the difference between a photograph of a filled-in form and the form itself: paper or a PDF is just the photograph, an e-invoice is the actual form. Hence the most common misconception:
This is NOT an e-invoice under the law
- A paper invoice sent by post
- A PDF attachment in an email
- A photo or scan of an invoice
This IS an e-invoice under the law
- A structured data file following the European standard (EN 16931, PEPPOL BIS format)
- Delivered over the PEPPOL network through a certified access point
- With a confirmation of dispatch and delivery for both parties
Who the obligation applies to
The duty is twofold — issuing and receiving — and it does not touch everyone equally:
A VAT payer established in Slovakia
Issues AND receives
From 1 Jan 2027, domestic invoices to businesses and public administration must be issued as e-invoices, and the company must equally be able to receive them.
A business that is not a VAT payer
Must be able to receive
A sole trader or a company without VAT registration does not have to issue e-invoices yet — but every business and legal entity must be able to receive them.
An ordinary consumer (household purchases)
Not affected
Sales to end customers (B2C) continue as before — receipts and invoices for households do not change.
Timeline: from the voluntary phase to the obligation
2026 · Q2
Voluntary phase
Companies can try electronic invoicing without penalties, bed in their processes, and prepare their accountant. Whoever starts now switches to the mandatory regime without a bump.
from May 2026
Provider certification
The Financial Administration certifies delivery-service providers — colloquially digital postmen (access points to the PEPPOL network) — and maintains a public register of them.
1 Jan 2027
The obligation
VAT payers issue domestic business invoices only electronically, and every business must be able to receive an e-invoice. The act also introduces electronic reporting of invoice data to the Financial Administration.
1 Jul 2030
European Union: cross-border invoices
The EU's ViDA package (VAT in the Digital Age) extends digital reporting to cross-border supplies within the EU.
How an e-invoice travels: the PEPPOL network in a nutshell
The PEPPOL network works like registered mail for data. You hand your invoice to your access point — a certified digital postman — and it delivers it through the network to your customer's access point. Both sides receive confirmation, and nobody opens or retypes the invoice along the way.
Today (until 31 Dec 2026)
- 1
You create an invoice in Word or an invoicing program
- 2
You email the PDF and hope it arrives
- 3
The customer retypes it into their books by hand
- 4
Typos, lost attachments, no delivery confirmation
From 1 Jan 2027
- 1
You issue an e-invoice in an application
- 2
Your access point sends it over the PEPPOL network
- 3
The customer's system reads it by itself — no retyping
- 4
Both parties hold a confirmation of dispatch and delivery
The journey of one e-invoice
Your company
Your access point ("digital postman")
PEPPOL network
Customer's access point
Customer
Slovak Financial Administration
The invoice travels straight to your customer — under the act only the data from it is reported to the Financial Administration, not the document itself.
How to prepare: 5 steps without panic
- 1
Find out whether you are a VAT payer — that determines whether you will only need to receive e-invoices or also issue them.
- 2
Choose a tool that can both receive and send e-invoices over the PEPPOL network — with no servers, certificates, or IT projects of your own.
- 3
Use the voluntary phase during 2026 — trying it now costs nothing, and the switch to the mandatory regime becomes boring instead of dramatic.
- 4
Agree with your accountant on the document flow — where documents are collected, who reviews them, and in what format they reach their software.
- 5
Tidy up the rest of your documents too — receipts and incoming invoices — so that from 2027 everything runs in one system instead of three boxes.
Where Aligna fits in
Aligna is built for the world after 1 January 2027: it sends and receives e-invoices through a certified Slovak access point to the PEPPOL network, and it does not merely deliver a received document — it verifies it, extracts its data, and prepares the pre-accounting entry, so the accountant receives finished data, not a pile of attachments. Receipts are verified in the eKasa registry of the Financial Administration already today.
E-invoicing 2027: questions and answers
Is a PDF invoice sent by email an electronic invoice?
No. To a computer, a PDF is just a picture — its data has to be retyped or extracted. An electronic invoice under Act No. 385/2025 Coll. is a structured data file following the European standard EN 16931, delivered over the PEPPOL network. From 1 January 2027, a PDF in an email no longer fulfils the legal obligation for domestic business invoices of VAT payers.
Do I have to receive e-invoices even if I am not a VAT payer?
Yes. The duty to issue e-invoices from 1 Jan 2027 applies to VAT payers for domestic supplies to businesses and public administration — but every legal entity and every business that is a taxable person must be able to receive an electronic invoice, regardless of VAT registration. If a VAT-paying supplier sends you an e-invoice, you must be able to take delivery of it.
What is a digital postman (access point)?
An access point — colloquially a digital postman — is a certified delivery-service provider that talks to the PEPPOL network on your behalf: it hands your invoices into the network and delivers incoming ones to you, with delivery confirmation. They are certified by the Slovak Financial Administration, which maintains their public register. Aligna connects through a certified Slovak access point, so you never have to choose or manage a postman yourself.
What happens if I do not prepare?
Receiving electronic invoices is a legal obligation from 1 Jan 2027, and your VAT-paying suppliers will send domestic invoices only this way. Without a tool for receiving, you cannot get at your own invoices in a usable form, and the Financial Administration can sanction unfulfilled tax obligations. The cheapest preparation is to try it during the voluntary phase in 2026.
Does e-invoicing also apply to eKasa receipts?
Cash-register documents from eKasa continue under their own regime — nothing changes for point-of-sale purchases. The new obligation concerns invoices between businesses and towards public administration. In Aligna, however, both worlds meet in one place: receipts are verified in the eKasa registry and e-invoices arrive via the PEPPOL network — the accountant receives everything in a single flow.