KSeF – questions and answers [Part 1]

January 25, 2024

The National Register of e-Invoices in Poland (PL: Krajowy Rejestr e-Faktur, KSeF) triggers a series of constant questions and answers. Will it be possible to use self-invoicing in KSeF? Can mistakes on an invoice result in rejection by the system? What to do if an invoice is issued to the wrong buyer? Will KSeF cover proformas? We answer these and several other questions in the first part of the most frequently asked questions about KSeF.

1. Can I use the self-invoicing procedure (so-called “self-billing”) in KSeF?

Yes – the KSeF system has been designed in such a way that it will be possible for the buyer to issue invoices on behalf of the seller, i.e. using the self-invoicing procedure. The seller must grant the buyer appropriate rights to issue such invoices. Please also remember that if we want to use the self-invoicing procedure within KSeF, it will still be necessary to reach an agreement with our supplier regarding the acceptance of issuing invoices.

2. Can KSeF reject an invoice?

Yes – it is possible for KSeF to reject an invoice. This may only occur when:

• the file/document structure does not match the logical pattern
• or it is entered into the system by an unauthorised person.

It is important to remember that an invoice that has been rejected is not considered issued. You cannot issue a correction or cancel it.

3. When you start using KSeF, is there no obligation to prepare the JPK_FA structure?

Concerning invoices issued in KSeF, as well as those sent to KSeF after failure or unavailability, there will no longer be an obligation to submit the JPK_FA file at the request of tax authorities. However, it is important to remember that this obligation will still exist for documents which will not be submitted to KSeF e.g. invoices for natural persons not running a business (consumers).

4. Will KSeF check the correctness of the data contained in the invoice? For example, are the net, gross and VAT amounts correct?

No – the system will not verify whether the amounts indicated on the invoice or the description of the service or goods are correct. The system will only check two things. One: the compliance of the XML file structure with the logical formula of an invoice structured in the XSD format. Second: the permissions to use KSeF of the person who made the document available.

5. What if an invoice is issued to the wrong buyer?

If an invoice is submitted to KSeF in which the wrong buyer is indicated, there must be 2 steps followed one by one. One: a corrective invoice should be issued “to zero”. Second: a new invoice with the correct buyer’s details should be issued.

6. Will I be able to issue a proforma invoice in KSeF?

No – even under the currently applicable regulations, a proforma invoice is not considered an official document for VAT purposes. Therefore, after the entry into force of KSeF, it will not be possible to submit proforma invoices via the system.

7. What date of completion should be indicated in the structured invoice in the case of periodic services?

In the case of invoices documenting services provided over a certain period (e.g. space rental in November 2024), the first and last day of the service should be indicated in the P_6_From and P_6_To fields, respectively. The format in which this data should be indicated is YYYY-MM-DD. This information should not be provided in a letter-descriptive format, e.g. November 2024.

More about KSeF

We encourage you to read the entire series of articles about the National e-Invoice Register in the series: “All about KSeF”:

• How to implement KSeF? 7 important questions
• 5 questions about KSeF
• Date of invoice issue in KSeF
• Will KSeF affect JPK?
• Unavailability of KSeF
• Fixed assets in a company – tax ABC

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