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What is it?

  • The National Electronic Invoicing System (KSeF) is a teleinformatics system for the management of electronic invoice flows, managed by the Director of National Tax Administration.
  • The purpose of the KSeF is to issue, receive, store structured invoices, access structured invoices and mark structured invoices with the identification number assigned in the KSeF. A structured invoice is considered to be issued on the day it is sent into the National Electronic Invoicing System.

What it’s for?

  • Manages XML files of structured invoices, according to the logical structure of the FA(1) e-invoice, and notifies rejection of structured invoices or inability to issue them.
  • It acts as a virtual postman for receiving, formally checking and sorting structured invoices to the addressees.

How does it works?

XML files of structured invoices are transmitted via communication channels to the KSeF. The system performs a formal check of the files and, if the structured invoice is correct with the logical structure of the electronic invoice FA(1), notifies the date and time of issue of the structured invoice and the structured invoice identification number assigned in the National Electronic Invoicing System, enters the invoices in the private area of the invoice portal and forwards them to the recipient.

If the structured invoice does not conform to the logical structure of the FA(1) e-invoice, KSeF will notify the date and time of the rejection of the invoice or the inability to issue the structured invoice, if the National Electronic Invoicing System is not available.

How it’s used?

XML files, i.e. structured invoice files, can be:

  1. prepared directly in the taxpayer’s financial and accounting programmes and sent to KSeF via API;
  2. sent using the free tools provided by the Ministry of Finance: the taxpayer’s KSeF application; or
  3. micro-entrepreneurs have access to the functionalities offered by the Ministry of Finance through the e-Mikrofirma web application.

Is it mandatory?

  • Currently, entrepreneurs can use the KSeF system on a voluntary basis.
  • During the optional period, structured invoices function on the market as one of the permitted forms of documenting transactions, alongside paper invoices and electronic invoices currently on the market.
  • Currently, the receipt of a structured invoice via KSeF is possible after the recipient has accepted this method of invoice receipt.
  • Mandatory as of 1 July 2024.
  • If the structured invoice is not sent to KSeF, it is deemed not to have been issued.
  • The issuance of structured invoices is not subject to acceptance by the recipient. A structured invoice is deemed to have been received by its purchaser, via KSeF, when KSeF assigns it a number that identifies it in the system.


Who will be obliged to issue electronic invoices?

Mandatory e-Invoicing will generally cover activities subject to VAT in Poland, including domestic supplies of goods and services between businesses (B2B), to public authorities (B2G). Consumer invoices (B2C) are not covered by KSeF.

The rules for issuing e-invoices will also be addressed to taxpayers using the so-called entity exemption (small entrepreneurs).

The obligation to issue structured invoices will apply to taxpayers performing activities covered by the invoicing obligation under Polish VAT law and having their registered office or a permanent establishment in Poland.

Will it be possible to send attachments to the invoice via KSeF together with the invoice?

It is not possible to attach structured attachments to invoices. However, it is possible to insert a link to such documentation in the text of the invoice. Additional information can be entered in the fields DodatkowyOpis/Additional Description, DodatkoweInformacje/Additional Information or possibly in the footer of the invoice. Attachments can also be sent separately outside KSeF.

Will the taxpayer be able to dispense completely with invoice archiving if he issues and receives all invoices using KSeF?

Electronic invoices will be stored in KSeF for a period of 10 years, starting at the end of the year in which they were issued. After 10 years, taxpayers are required to archive invoices outside of KSeF until the tax statute of limitations expires. Invoices issued exclusively by the system are archived in KSeF.

What mandatory and/or optional fields must be included in the FA(1) invoice structure?

The invoice to be sent must conform to the logical structure FA(1). The compulsory nature of a given field derives in particular from the content of the applicable rules. The logical structure of the electronic invoice, in addition to the elements whose presence is regulated by Articles 106a – 106q of the VAT Act, also contains elements whose use is completely voluntary and arbitrary. Their inclusion in the structure results from the business practice observed in the market. These are so-called additional elements of the invoice, which do not derive from VAT law and whose use in the invoice is not prohibited. These fields may be left unfilled, even if such data is available.

Completely optional nodes are the Rozliczenie/Settlement, Płatność/Payment, Warunki Płatności/Payment Conditions and Stopka/Piè nodes. When compiling voluntary nodes, it may be necessary to complete the mandatory fields contained in these nodes. The Zamówienie/Order node applies only to advance invoices and their adjustments. For such invoices, the FaWiersze/FaRows node is not filled in. The other fields are filled in according to the legal requirements for the specific case documented by the invoice.

When is an invoice considered issued?

The date of the invoice is the date on which it is sent to KSeF. An invoice is considered to have been issued on the day on which it is sent to KSeF, pursuant to Section 106na(1) of the VAT Act, i.e. the moment it enters the system, regardless of any subsequent processing. Information on the date of transmission will be included in the UPO. This date is also included in the number assigned by KSeF.

When is a received invoice considered?

Date of issue of the KSeF number is the date of delivery of the invoice to the recipient. During the optional period, in the absence of the buyer’s consent to receive the structured invoice in KSeF, the seller may transmit the structured invoice in KSeF by other means, e.g. by e-mail (PDF), by post (hard copy). In this case, the date of sending the invoice to KSeF is binding for the seller, whereas the buyer is not entitled to the deduction until he receives the invoice outside KSeF.

What happens if an invoice sent to KSeF is rejected?

A rejected invoice is not considered to have been issued, so it cannot be corrected or cancelled. If an invoice is rejected by the system, it is up to the taxpayer to decide whether to correct it and send it back to KSeF. Rejection of an invoice by the system can only occur because the file structure does not match the logical schema or because it was entered into the system by an unauthorised person. We encourage the implementation of mechanisms in invoicing systems that check the compliance of the xml file with the logical structure template before sending the file, which will in practice eliminate the situation described in the question.

What do I have to do to start using electronic invoicing on KSeF?

Structured invoices can be:

  1. prepared directly in the taxpayer’s financial and accounting programmes and sent to KSeF via API;
  2. sent using the free tools provided by the Ministry of Finance: the taxpayer’s KSeF application; or
  3. micro-entrepreneurs have access to the functionalities offered by the Ministry of Finance through the e-Mikrofirma web application.
Will invoices from foreign suppliers without a Polish PIN have to be reported to KSeF?

KSeF is not used to report invoices from foreign suppliers.