Webinar replay: E-invoicing in practice | Q&A part 3

Less than two months remain until mandatory e-invoicing takes effect. In the final part of our Q&A webinar series, we covered the upcoming amendment to the VAT Act, penalties, the correct mapping of VAT categories and the practical situations companies most often face when preparing for e-invoicing. Watch the webinar recording or read a summary of the key answers.

What we covered in the webinar

The webinar was led by our tax experts Ivana Bošková and Lucia Ondrejková. Here is an overview of the nine topics they covered.

1. What changes will the upcoming VAT Act amendment bring?

At the time of the webinar, the draft amendment to the VAT Act, which also amends the e-invoicing rules, was being discussed by parliamentary committees. If approved, it will bring the following main changes:

• self-billing: where the customer issues the invoice on behalf of the supplier, the invoice data will be reported to the Financial Administration by the customer’s digital postman, not the supplier’s, as previously communicated,
• corrective documents for invoices from 2026: corrective documents for invoices that were not issued as e-invoices may, even after 1 January 2027, be issued in the same format as the original document, with issuing them as e-invoices being voluntary,
• exemption for landlords: taxable persons that are not VAT payers and lease real estate exempt under Section 38(3) of the VAT Act without including it in their business assets will not need a digital postman to receive invoices, provided the lease is their only activity as a taxable person.

In the meantime, the Financial Administration has also revised its interpretation of correcting an invoice by cancelling the original document with a 100% credit note and issuing a new one. The credit note carries code 381. Under the original interpretation, the new invoice was to carry debit note code 383. According to the latest response from the Financial Administration, however, it will be a standard invoice with code 380.

2. What are the penalties for failing to comply with e-invoicing obligations?

Under the current wording of the law, the tax office may impose a fine of up to EUR 10,000 if a VAT payer fails to meet its reporting obligation, reports data late, does not report all required data or reports incorrect data. For repeated breaches, the fine can reach up to EUR 100,000.

When determining the amount of the fine, the Financial Administration is to take into account the seriousness and duration of the breach. It should not impose fines for an obvious error that the company subsequently corrects. Nor should it impose fines where the digital postman demonstrably fails to send an invoice within 15 days due to technical problems, such as a power or internet outage. Once the problem is resolved, however, the documents must be sent retrospectively.

The draft amendment also provides for a grace period during the first six months of mandatory e-invoicing. During this period, the tax office should not penalise issuing an e-invoice after the 15-day deadline or incorrectly mapped data in the XML format. Instead, it should notify the taxable entity to bring its settings into line with the law.

3. What if a customer subsequently notifies the supplier that it should have received an e-invoice?

From 1 January 2027, a supplier may issue a paper or PDF invoice to a customer recorded in its system as a non-taxable person, and only afterwards learn from the customer that it is a taxable person.

The law currently does not specify a deadline by which the customer may notify the supplier of this fact. However, the supplier is required to issue an e-invoice within 15 days of the subsequent notification. We recommend cancelling the original invoice and issuing a new one through the e-invoicing system. It is advisable to state in an optional field of the e-invoice that it was issued based on the customer’s subsequent notification, and to archive the notification itself in case of a tax audit.

💡 Recommendation: before mandatory e-invoicing takes effect, review your customer and supplier databases, fill in any missing data and verify that persons recorded as non-taxable are in fact non-taxable.

4. What are VAT categories and VATEX codes?

When converting an invoice to the XML format, a VAT category (field BT-118) must be stated for each line item. The category is not determined by the type of goods or the amount of tax, but by the legal regime of the supply under the VAT Act. For exempt supplies and supplies under special schemes, a VATEX code (field BT-121) is stated in addition to the category, specifying the exact type of exemption. Field BT-120, containing a text description of the reason for the exemption, is supplementary.

Basic mapping for Slovakia:

What to watch out for:

• code Z is used only for a genuine zero VAT rate set by law, which Slovakia currently does not have, and it is not used, for example, for reverse charge,
• code K for supplies of goods to another Member State is not yet mandatory, as mandatory e-invoicing from 1 January 2027 applies only to domestic supplies, but you can voluntarily send e-invoices to partners registered in the Peppol network even before 1 July 2030,
• an overview of VATEX codes by type of exemption is available in the Q&A material on the Financial Administration website, which is updated on an ongoing basis.

5. Can items at the standard rate and items outside the scope of VAT be combined in a single e-invoice?

This is a common situation, for example when invoicing accommodation together with the accommodation tax. The EN 16931 standard and the Peppol BIS Billing 3 specification currently do not allow category S (standard rate) and category O (outside the scope of tax) to appear on the same e-invoice. Such a document will fail validation. There are two solutions:

• issue two separate documents,
• mark the items outside the scope of tax with code E (exempt from tax) instead of code O and state in field BT-120 that the supply is “outside the scope of tax”.

The second approach is the official interpretation of the Financial Administration. The EN 16931 standard is updated approximately twice a year, so this rule may change in the future.

6. What applies if the supplier is not a VAT payer and the customer is?

A supplier that is not a VAT payer is not required to issue e-invoices, but may join the e-invoicing system voluntarily. In that case:

• its supply is considered to be outside the scope of VAT, so it states code O (outside scope of tax) for individual line items,
• the invoice must not include the VAT ID of either the supplier or the customer,
• the customer must therefore be identified in another way, and the Financial Administration recommends using the company ID (IČO) or tax ID (DIČ).

If the customer insists on stating its VAT ID, the invoice will fail validation in the Peppol network and the supplier will have to deliver it as before, for example by email or post.

7. What is the tolerance for VAT calculation?

An e-invoice sometimes fails validation even though all the data appear to be correct. A common reason is the way VAT is calculated. The EN 16931 standard recommends first adding up the tax bases for each rate and only then calculating VAT on the total. Many accounting systems, however, calculate VAT on each invoice line separately, which leads to small rounding differences when an invoice has many items.

The validation rules take this into account. All amounts are rounded to two decimal places regardless of the currency, and a difference of up to and including 0.99 of the currency unit is tolerated.

8. How do you change your digital postman?

You can change your digital postman at any time. There is no need to wait for the end of the voluntary phase or for 1 January 2027. The procedure is as follows:

1. termination of the contract with the original provider,
2. deregistration of the entity in the central SMP register, which the original digital postman arranges no later than three working days after the contract ends,
3. confirmation of the deregistration, which the original digital postman sends to the customer,
4. registration with the new digital postman.

Notice periods are the most common cause of delays, so check your contractual terms in advance. The state does not intervene in a change of digital postman. The contractual relationship is solely between the business and the service provider.

9. How long must e-invoices be archived?

A VAT payer is required to archive e-invoices in a format that allows their automated electronic processing, i.e. in the XML format. Keeping only the PDF version does not meet the legal obligation. The archiving period is 10 years from the end of the calendar year to which the invoice relates. What to watch out for:

• we recommend also keeping the confirmations that invoices were sent to the digital postman, as they may serve as evidence in a tax audit,
• responsibility for archiving lies with the VAT payer, not the digital postman, and some digital postmen keep invoices only for a limited time, for example three months, so check their contractual terms,
• for some invoices, particularly those relating to capital goods and real estate, the purpose of use must be monitored for up to 20 years, so do not delete them automatically after 10 years.

What’s next?

At the time of the webinar, the draft amendment to the VAT Act had not yet been approved. In addition, several accounting software providers and digital postmen will only be testing some features at the end of November and in December. If further significant changes or questions arise, we are considering one more Q&A webinar in December. We will share updates on our LinkedIn profile.

The information in this article is current as of 5 November 2026.

More webinars

Our Transfer pricing in practice webinar series, led by our colleague Ulrika Gajdošová, also continues. You can find the dates and registration on the webinar series page.