Can I use multiple e-invoice series for branches or systems?
Short answer
Yes. § 74 ods. 1 letter c) requires the serial number of the invoice, and the official explanations of the Financial Administration allow one or more series of numbers, for example by branch or type of delivery. However, each number must uniquely identify the invoice. For multiple ERPs, use a distinguishable prefix or other controlled scheme to avoid collisions.
More series
A branch, system or delivery type can have a separate line.
Unambiguity
The serial number must identify one invoice.
BT-1 without rewriting
The actual number including the prefix belongs to the XML.
Central rule owner
The company must be able to explain the creation of the number and prevent collisions.
Conclusion
Multiple number ranges are allowed. The prerequisite is unambiguous identification, consistent BT-1 and collision management.
the VAT Act · current FAQ of the Financial Administration of the Slovak Republic on e-invoice · Peppol BIS Billing 3.0
Not legal advice. Machine-translated answer, not yet manually reviewed. For the exact wording, see the Slovak original.