Which APIs are needed for e-invoice?
Short answer
The law does not require a particular API. A business issuing only a few invoices may use a provider portal or invoicing application without any API integration. ERP systems, e-shops and automated workflows commonly use APIs to create and validate e-invoice, submit it through a delivery-service provider, receive delivery statuses and exchange data between systems.
XML inspection
The API should be able to return errors from XSD, EN 16931 and the profile.
Partner connector
Shipping goes through a certified delivery partner.
Webhook or polling
ERP needs to know what happened to the document.
Evidence package
Save XML, hashes, reports, statuses and confirmations.
Conclusion
Choose APIs according to the workflow and systems being integrated; the law does not mandate a specific API.
Sources
- Law no. 222/2004 Z. z. Coll. on VAT, § 76a
- Law no. 222/2004 Z. z. Coll. on VAT, § 85o
- EN 16931 and Peppol BIS Billing 3.0
FAQ of the Slovak Financial Administration for e-invoice, July 2026
Not legal advice.