What is KSeF?
Author: Domeny.ForSale editorial team Published
In brief: KSeF, short for Krajowy System e-Faktur (Poland’s National e-Invoicing System), is a state system used to issue, receive and store structured invoices. Such an invoice has a defined data format, rather than merely the appearance of a PDF document. For a business, using KSeF means changing invoice workflows and preparing software, access permissions and procedures; the scope of the obligation must be checked against current legislation and announcements from Poland’s Ministry of Finance.
What KSeF is and how it differs from a PDF invoice
The National e-Invoicing System is a solution provided by Poland’s tax administration. Its purpose is to handle invoices in a uniform format that allows software to read document data without manually re-entering amounts, NIP tax identification numbers or sales line items.
A structured invoice is an electronic document saved in accordance with an officially defined XML structure. XML is a format that describes data using named fields. The software therefore knows which value represents the seller, date, net amount or VAT.
Sending a PDF by email does not make it a structured invoice. It may provide a readable visual representation of invoice data, but the document’s appearance alone does not establish that it was issued through KSeF. Similarly, a scan of a paper invoice is not a document in the required structure.
KSeF does not replace the entire accounting process. It does not handle a business’s tax settlements, make bank transfers or determine whether a particular expense can be treated as a deductible cost.
How invoices are issued and received
In the standard online mode, the seller prepares the invoice data in software connected to KSeF or in an appropriate tool provided by the administration. The document is then sent to the system, which checks its compliance with technical requirements. Once accepted, the invoice receives a number identifying it within KSeF.
The KSeF number is not the same as the invoice number assigned by the seller. The software should allow the two identifiers to be linked and the document’s status to be checked. Simply clicking “send” is not sufficient confirmation that the invoice has been accepted.
A typical workflow looks like this:
- The seller enters the transaction data and approves the document.
- The software sends the invoice to KSeF and checks the processing result.
- Once it has been accepted, the software saves the KSeF number and the official acknowledgement of receipt, known as UPO.
- The buyer or an authorised accounting firm downloads the document from the system.
For example, an agency issues an invoice for website management services. Rather than merely emailing a PDF to the client, it submits the invoice data to KSeF. The client’s accounting team can download the data into its own software, but it still needs to establish what the purchase relates to and who should approve payment.
Acceptance of a document by KSeF does not confirm that the entire transaction, the VAT rate or the right to deduct tax is correct. Technical validation does not replace accounting checks.
Who is required to use KSeF
Do not assume that the obligation applies to every business and every invoice under identical rules. Relevant factors may include the taxpayer’s status and place of establishment, the type of transaction, the recipient of the document and transitional provisions. Being exempt from VAT is not, in itself, sufficient grounds to conclude that KSeF does not apply to a business.
Because implementation rules and exceptions depend on current law, you need to confirm the following in the Ministry of Finance’s official KSeF materials:
- the date on which a particular business becomes subject to the obligation and the conditions for any transitional relief;
- the rules for consumer invoices and transactions with foreign entities;
- how to handle corrections, attachments and special types of documents;
- current technical requirements and the rules that apply when the system is unavailable.
It is also important to distinguish the obligation to issue invoices from the rules for receiving them. A business should establish both processes rather than preparing only its sales department. This description explains how the system works; it is not individual tax advice or an assessment of a particular business’s obligations.
How to prepare your business and accounting firm
The first step is to check whether your software supports the current invoice structure and communication with KSeF. A supplier’s statement that “we support KSeF” is not enough: ask about downloading purchase invoices, checking statuses, corrections and error handling. Confirm the integration price and the range of features with the software supplier.
The second step is access permissions, meaning determining who can perform each action on behalf of the business. The owner, a sales employee and an accountant do not always need the same access. Do not share login credentials; use the authentication and permission-management methods appropriate to the system.
Also establish who checks new purchase invoices, approves their validity and oversees payments. Automatically downloading a document should not trigger a bank transfer without checks. Agree on the division of responsibilities with your accounting firm so that documents are neither posted twice nor overlooked.
What to do in the event of an error or outage
A file being rejected by KSeF and an error in an invoice that has already been accepted are different situations. In the first case, you need to check the message, correct the cause and resend the file following the appropriate procedure. In the second, you should not simply overwrite the document in your software — you must apply the relevant correction rules.
Prepare a procedure for system unavailability based on the current rules for offline and emergency modes. Confirm the requirements for document markings, delivery to the recipient and deadlines for subsequent submission to KSeF.
Before launching the process, test one sale, one purchase and one correction in the test environment. This will show whether the software, staff and accounting team can handle a document from data preparation through to accounting and settlement.
See also: What is GitLab?
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