Code O

How should a non-VAT payer invoice a VAT payer using e-invoice voluntarily?

Short answer

A supplier that is not a VAT payer does not invoice the supply as subject to VAT. If the supplier voluntarily sends a structured invoice through a delivery service, the lines are generally mapped using tax category O, outside the scope of VAT, in accordance with the applicable profile rules. The supplier must not state a VAT identification number that it does not have.

Non-payer

None VAT

It does not calculate VAT as a payer.

Customer

It can be a payer

The status of the customer does not change the status of the supplier.

Code O

Out of scope

It is used for transactions outside of the VAT logic of the payer.

BR-O

Pay attention to the VAT number

For category O, VAT party identifiers do not apply.

Detailed explanation

It is crucial to distinguish between the status of the customer and that of the supplier. The fact that the customer is a VAT payer does not make a non-VAT-registered supplier a VAT payer. A non-VAT-registered supplier therefore does not calculate VAT, does not state the VAT rate as a VAT payer, and must not provide a fictitious VAT registration number. When applying Peppol rules, the restrictions for category O must also be observed, in particular the rules of the BR-O group, which prohibit the inclusion of VAT identifiers on documents not subject to VAT.

As set out in the law and technical rules

The obligation to issue e-invoices under Section 85o applies to taxable persons under Sections 4, 4b or 4c. A non-VAT-registered person may, in certain cases, be the recipient of e-invoices or participate voluntarily, but this does not alter their tax status.

Practical examples

A sole trader who is not a VAT payer invoices a service to a Slovak s.r.o. that is a VAT payer; they do not charge VAT and do not state their own VAT registration number.
A non-registrant voluntarily sends an XML file via the postal service; they map the items to category O in accordance with the profile rules.
If the supplier later becomes a VAT-registered business, they apply different invoicing rules from the date of registration.

Common misconceptions

“The customer is a VAT-registered business, so I must add VAT.” No. What matters is the supplier’s status and the nature of the supply.
“A non-VAT-registered party may provide a fictitious VAT registration number.” No. The details must be accurate.
“Code O means VAT exemption.” No. ‘O’ means ‘outside the scope’ or ‘not subject to VAT’; an exemption falls under a different category.

Conclusion

Voluntary e-invoice does not change the supplier’s tax status: do not invent VAT data and map the supply under the applicable category O rules.

Legal and technical basis

Act No. 222/2004 Coll. on VAT, Section 4
Act No. 222/2004 Coll. on VAT, Section 85o
Peppol BIS Billing 3.0 – BR-O rules, in particular BR-O-02

Official cases from the Slovak Financial Administration’s FAQs

The following questions and answers are taken from the current July FAQ from the Financial Administration and have been assigned to this topic. Grouping the cases prevents the creation of duplicate pages, whilst retaining the full answer and the exact wording of the question.

Example No. 42: Non-VAT payer → VAT payer and code ‘O’ (Out of scope): How should invoicing be handled if the supplier is not a VAT payer and the customer is a VAT payer? Transactions (supplies of goods and services) by a non-VAT payer are not subject to value added tax. If a non-VAT payer voluntarily joins the electronic invoicing scheme from 1 January 2027, i.e. delivers e-invoices via the delivery service (the Peppol network), they should apply code O – Not subject to VAT to the individual items on their invoices.

In this case (non-VAT payer → VAT payer), the supply is not subject to VAT; therefore, the VAT category code ‘O’ (Out of scope) is used. However, according to the Peppol BIS 3.0 BR-O-02 rule, neither the supplier’s nor the customer’s VAT registration number may be stated on the invoice when this code is used. The customer must therefore be identified without a VAT registration number (e.g. company registration number, tax identification number). This procedure is also acceptable from a legislative perspective: • the VAT Act does not apply to the transaction in question, • the Accounting Act does not require the VAT registration number to be stated if the customer can be identified by other means (company registration number, tax identification number). At the same time, please note that should the customer request that their VAT registration number be included on the invoice, it will not be possible to issue such an invoice in accordance with the Peppol BIS 3.0 rules. In such a case, it is necessary to choose an alternative method of delivering the invoice outside the Peppol network.

Primary source: Financial Administration of the Slovak Republic, FAQ 9/VAT/2025/IM k e-invoice, July 2026 update. Processed and checked on 13 July 2026.