KSeF – National e-Invoice System
Starting from April 1, 2026, invoices for all business users will be issued in a structured format (XML) and sent to the National e-Invoice System (KSeF).
If you are a business user, both the invoice format and the method of receiving invoices will change — from that moment, invoices will be available directly in the KSeF system.
If you are an individual user and do not run a business, the introduction of the KSeF system will not affect the way you receive VAT invoices — nothing will change for you. The VAT invoice will still be available in your Online Subscriber Account (IKA) – Viking Account.
The National e-Invoice System (KSeF) is a government-run, centralized platform used for issuing, receiving, and storing so-called structured invoices. In 2026, the system will become mandatory for all entities that issue and receive invoices.
Every business entity will be required to issue and receive invoices through KSeF.
KSeF provides a uniform standard for electronic invoices across the country and automates the exchange of documents between companies. Thanks to this system:
- you have continuous access to invoices issued in KSeF for up to 10 years,
- you do not need to store or print them yourself,
- you eliminate the risk of losing or damaging documents.
You can find more information about KSeF on the website of the Ministry of Finance.
Invoices issued through the KSeF system will differ from those we have issued so far. Instead of a PDF file, the invoice will be a structured invoice in the form of digital data (XML format) or a PDF visualization.
To make it easier for you to adapt to the new solution, we will provide visualizations of invoices issued in KSeF in your Online Subscriber Account (IKA) – Viking Account.
The visualization will include:
- Id_KSeF – the invoice number assigned by the KSeF system (if available at the time the visualization is sent)
- QR code – allowing you to access the invoice in KSeF and verify its authenticity
Please note: The invoice visualization is not the original VAT invoice within the meaning of tax regulations. The visualization is provided for informational purposes only.
The official document will be available exclusively in the KSeF system, and you will need to download it directly from KSeF yourself.
The method of providing invoice details will remain unchanged, regardless of whether you are a business or individual user.
The document will still be available in the Online Subscriber Account (IKA) – Viking Account.
Company details assigned to a NIP number are automatically retrieved from the GUS (Statistics Poland) database. Please note that once an invoice has been issued in the KSeF system, it cannot be edited.
Any changes will only be possible by issuing a corrective invoice.
If you are a business user, but for some reason your NIP number has not appeared on your invoices so far, please contact us immediately.
If the NIP number is incorrect, the invoice will not be successfully delivered through the KSeF system.
In addition to the mandatory issuance of structured invoices and their submission to KSeF for business users, we will continue to provide a visualization of the invoice in the Online Subscriber Account (IKA) – Viking Account.
From April 1, 2026, receiving invoices from Mobile Vikings via the National e-Invoice System (KSeF) will be mandatory for all companies — including corporate entities and sole proprietors — regardless of their turnover level.
With the introduction of the KSeF system, starting from April 1, 2026, we will no longer issue or send invoice duplicates.
Invoices will always be available in the KSeF system (for 10 years). At any time, you can download the invoice visualization by logging into your Online Subscriber Account (IKA) – Viking Account.
An important change is the elimination of correction notes. This means that starting from April 1, 2026, it will no longer be possible to correct minor errors on an invoice using a correction note, such as a mistake in the company name or address.
If you notice any inaccuracies, please contact us and provide the correct details. After verifying the validity of the request, we will issue a corrective invoice.
Frequently Asked Questions
The original VAT invoice is available exclusively in the KSeF system.
After the invoice is issued and accepted in KSeF, we will make its visualization available in the Online Subscriber Account (IKA) – Viking Account.
The visualization includes a QR code, which allows you to quickly find and download the invoice directly from the KSeF system.
An invoice in the KSeF system is issued based on the correct company NIP number. If the NIP number is incorrect, the invoice will not appear in the system on your account.
If the NIP number is correct, but the invoice is still not visible in KSeF, it may mean that the document has not yet been successfully processed or delivered in the system.
No, the KSeF system does not send automatic notifications when an invoice is issued, so you need to check this yourself.
The Ministry of Finance provides the KSeF Taxpayer Application (online version) and the KSeF Mobile Application (available for smartphones). After logging in, you can check all issued invoices there.
Compare the invoice received from KSeF with the visualization available in the Online Subscriber Account (IKA) – Viking Account.
The visualization includes a QR code that confirms the invoice has been registered in the KSeF system. After entering additional data, it also allows you to download the invoice directly from the system.
The KSeF system also allows you to report invoices to the tax administration if you suspect fraud.
No. Once an invoice is accepted in the KSeF system, it becomes a legal document and cannot be edited or modified.
If you notice any inaccuracies, please contact us and provide the correct details. After verifying the validity of the request, we will issue a corrective invoice.
What will your invoice look like
We send a visualization of the structured invoice (KSeF invoice).
- Visualization
You will receive an invoice visualization from Mobile Vikings. The original invoice must be downloaded directly from KSeF.
The visualization is for informational purposes only and is intended to verify the invoice data.
- Change for Local Government Units and VAT Groups
Under the address details, you will also find the NIP number of the Recipient (third party).
- QR Code
The visualization includes a unique QR code containing the invoice number in KSeF.
The QR code confirms that the invoice has been correctly issued through the KSeF system.
In the event of a temporary failure or unavailability of the KSeF system, an invoice may be issued in OFFLINE24 mode. In such a case, the invoice will include two QR codes.
We will send the invoice to the KSeF system as soon as possible — immediately after the cause of the failure or unavailability on the KSeF side has been resolved.
- VAT Invoice
On the first page of the document, you will find information indicating that it is a VAT invoice, not an invoice visualization.
- Two QR codes
The document will contain two QR codes:
- one marked “OFFLINE”
- the other marked “CERTIFICATE”.
In the event of a prolonged KSeF system failure, we will issue an invoice without QR codes. Such a document will look the same as invoices issued before the implementation of KSeF.
