KSeF 2026 Questions and Answers

Start with an audit of your own company. Ask yourself:

• 1.How do I issue invoices today? (Paper, Excel, software?)
• 2.How do I receive invoices today? (Email, mail, in person?)
• 3.Will my current software be integrated with KSeF? Then choose the right tool, such as mpFaktura, which is fully ready for KSeF.

The connection is very simple and one-time. You need to:

• 1.Download the latest version of mpFaktura.
• 2.Enable KSeF support and select the appropriate schema version - FA(3).
• 3.Authenticate in KSeF directly from the application.
• 4.Generate KSeF certificate and offline certificate.

• 1.Diagnose your situation: How do you issue and receive invoices?
• 2.Choose a tool: Test mpFaktura with a free 30-day trial period.
• 3.Configure the connection: Generate a token and connect the software with KSeF.
• 4.Test: Send a few test invoices, download purchase invoices.
• 5.Train your team: Make sure everyone knows how to use the new system.
• 6.Establish procedures with your accounting office.

This is a key element of implementation. You should:

• 1.Train the team on changes and new procedures.
• 2.Designate people responsible for invoicing and document receipt.
• 3.Grant them appropriate permissions in KSeF.
• 4.Create internal document workflow procedures.
• 5.Conduct tests on the demo version of KSeF or in mpFaktura software.

• 1.Launch the mpFaktura software.
• 2.Issue an invoice - just as you have done before.
• 3.Change the invoice status to: "Approved".
• 4.Click: "Send to KSeF". The invoice will be validated, converted to XML format, and sent to KSeF. Upon acceptance, you will receive a UPO with the KSeF number.

In mpFaktura:

• 1.Select the document you want to correct.
• 2.Enter the corrected data (e.g., new quantity, price, VAT rate).
• 3.Change the correction status to "Approved".
• 4.Click: "Send to KSeF". The correction must include the KSeF number of the corrected invoice - mpFaktura fills this in automatically.

Check:

• 1.Whether the contractor actually sent the invoice to KSeF (and not just issued it in their software).
• 2.Whether the invoice was issued to the correct tax ID number.
• 3.Whether there is a synchronization delay (refresh the invoice list in mpFaktura).

You have several options:

• 1.Grant permissions - the accountant will download invoices from KSeF themselves.
• 2.Export to XML - download invoices and send XML files by email.
• 3.Shared software - use the same software (e.g., mpFaktura Online), where the accountant has access to your documents.

In mpFaktura:

• 1.Go to "Management" -> "KSeF Management".
• 2.Go to the "Settings" tab and in the "General Options" section, specify the users responsible for downloading documents from KSeF, checking statuses/UPO, and sending documents.

KSeF revolutionizes this cooperation. The most popular models are:

• 1.Working together on one software - The office provides you with software where you both have access to documents.
• 2.The office issues invoices for you - You provide the data, and they issue invoices on your behalf.
• 3.You issue, the office downloads - You issue invoices in mpFaktura, and the office independently downloads them from KSeF.

• 1.Revoke permissions from the current office.
• 2.Grant permissions to the new office.
• 3.Provide the new accounting office with necessary information about existing documentation.

• 1.You issue an invoice in mpFaktura.
• 2.The software marks the invoice with a special QR code and an offline mode annotation.
• 3.After access to KSeF is restored, you send the invoice to the system. An offline invoice is a valid document from the moment of issuance.

The process is intuitive:

• 1.You authenticate in KSeF.
• 2.You issue an invoice as usual in the software.
• 3.You click "Send to KSeF" - the invoice is submitted to the system and receives a number.
• 4.You can download purchase invoices automatically or manually.

Advance invoices are sent to KSeF like regular invoices. In mpFaktura:

• 1.Select document type - "Advance invoice".
• 2.Specify the buyer and add items.
• 3.Enter the advance amount.
• 4.Change status to "Approved".
• 5.Click "Send to KSeF". The system will calculate VAT only on the advance amount.

In mpFaktura:

• 1.Open the document for which you want to issue a final invoice.
• 2.Click "Next advance".
• 3.Check the "Final advance" option.
• 4.The system will automatically deduct previously paid advances and calculate the amount due.
• 5.Change status to "Approved" and send to KSeF.

In mpFaktura:

• 1.In annotations, check the appropriate procedure (e.g., "Margin scheme - used goods").
• 2.In the item, enter the subject of sale and gross price.
• 3.As the VAT rate, select "Margin scheme". VAT is calculated on the margin (difference between purchase and sale price), but you make this calculation outside the invoice, for VAT return purposes.

• 1.Do not share your token/certificate with third parties.
• 2.Regularly check the list of authorized persons.
• 3.Revoke access for former employees.
• 4.Use strong passwords for your Trusted Profile.
• 5.Use trusted software like mpFaktura.

• 1.Incorrect buyer's tax ID number - always verify the tax ID before issuing an invoice.
• 2.Failure to send to KSeF - make sure the invoice reached the system.
• 3.Incorrect VAT rate - check the rate for the given product/service.
• 4.Missing bank account number - add it if you expect a bank transfer.

• 1.Test before launch - send a few test invoices in the demo environment.
• 2.Train employees - make sure everyone knows the procedures.
• 3.Update your software - use the latest version of mpFaktura.
• 4.Check UPO - verify that invoices reached KSeF.
• 5.Carefully check data before sending - invoices cannot be canceled.