GUIDE 101 for electronic invoicing

Everything you should know about electronic invoicing

General rules for issuing, receiving and accessing structured invoices

Structured invoices are issued and received by taxpayers via a teleinformatics system, i.e. the National Electronic Invoicing System (KSeF).

Currently, the test phase period is underway in which the use of structured invoices requires acceptance by the recipient of such an invoice, e.g. by accepting the relevant message in the e-MicroSignature application or by downloading invoices from the system itself via the API (a set of rules strictly describing how programmes or subroutines communicate with each other).

The rules governing the issuance of duplicate invoices do not apply to structured invoices, as it will not be possible to lose or destroy an invoice issued via KSeF.

Authorisation to issue, receive and access structured invoices and authentication of authorised parties

The solution is based on a credential model, i.e. authorisation of the person in the system is required. Invoices will be prepared directly in the taxpayer’s local or cloud-based financial and accounting systems and sent to the system via an API. This will require the taxpayer to authenticate in the system. Once authenticated in the system, the taxpayer will be able to view the structured invoices issued and received, and will be able to upload any invoice or invoice package in xml format or convert to PDF. In addition to the taxpayer, structured invoices can also be issued or viewed by a person authorised to access KSeF. The possibility of authorising the issue of structured invoices on behalf of the taxpayer or access to these invoices for, for example, an accounting department or a specific person has been introduced.

All invoices, including adjusting invoices, can be drafted in the taxpayer’s accounting and financial system and sent to KSeF via the API. Once an invoice is uploaded, KSeF will assign a number that identifies it in the system with a date and time. When the invoice structured by the system is assigned an identification number, the invoice is considered to have been issued and received at the same time.

Functions performed by KSeF

KSeF is used to issue, receive, store structured invoices, access structured invoices and mark structured invoices with the identification number assigned in KSeF.

A structured invoice is considered to be issued on the day it is uploaded into the national e-Invoicing system.

Once the e-invoice has been uploaded to KSeF, the system will notify the entrepreneur of:

  • the date and time of issue of the structured invoice and the identification number of the structured invoice assigned in the system and the date and time of its assignment
  • the date and time of rejection of the invoice in the event of non-compliance with the structured invoice template and the impossibility of issuing the structured invoice if KSeF is not available.



  • KSeF is used to issue, receive, store structured invoices
  • Authorisation of the person in the system is required
  • A test phase is in progress to test the sending and receiving of invoices


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