# Create and Submit KSeF Invoices on Multiplier
As Poland transitions to the mandatory National e-Invoice System (KSeF) starting in 2026, paper and standard PDF invoices will no longer be legally valid for B2B transactions.
Therefore, to ensure your cross-border invoices are legally compliant and processed for payment, you must generate your invoices using a KSeF-integrated tool, clear them through the Polish government system, and provide Multiplier with the official KSeF-generated PDF visualization.
The process is divided into two parts:
1. [Create a KSeF invoice](#create-a-ksef-invoice)
2. [Submit the KSeF invoice on Multiplier](#to-submit-an-invoice)
### Create a KSeF invoice
Learn how to create and submit KSeF invoices on Multiplier:
1. **Choose an Invoicing Tool**
You don’t need to purchase any software to meet this requirement. The Polish Ministry of Finance provides several free tools, although you may choose to use commercial software if you prefer. Here is a list of some free government and commercial tools.
**Free Government Tools**
* KSeF Taxpayer Web Application (Aplikacja Podatnika KSeF): A free online portal provided by the Ministry of Finance where you can log in, manually enter your invoice details, and issue the invoice directly to the government.
* KSeF Mobile App (Aplikacja Mobilna KSeF): A free smartphone application that allows you to issue, view, and manage invoices directly from your mobile device.
* e-Mikrofirma: A free tool linked to your e-Tax Office (e-Urząd Skarbowy) account that lets you issue invoices and automatically transfers the data to your VAT records.
**Commercial tools**
* Third-Party Accounting Platforms: If you already use commercial Polish accounting software (such as Subiekt, Optima, enova365, or Comarch), these platforms are updated to integrate directly with the KSeF API. You can generate the invoice in your software as usual, and it will push the required XML file to KSeF automatically.
2. **Log in and Authenticate**
To use the free government tools, you must authenticate your identity. You can log into the KSeF portal using:
* Trusted Profile (Profil Zaufany)
* Qualified Electronic Signature
* Qualified Electronic Seal (for companies)
* KSeF Certificate (available from February 2026)
3. **Enter Your Invoice Details**
When creating the invoice in your chosen tool, the system will format your data into the mandatory FA(3) XML schema behind the scenes. Ensure you include the following for your cross-border invoice to Multiplier:
* **Buyer Details:** Multiplier's legal entity name, Singapore address, and UEN (Tax ID).
* VAT Details: Because this is a cross-border supply of services to a non-EU entity, you should apply a 0% or "NP" (Not Subject to Polish VAT) rate.
* **Reverse Charge:** You must include "Reverse Charge" (or odwrotne obciążenie) wording. You can type this, along with specific payment terms or foreign bank account details, into the DodatkowyOpis (Additional Description) or StopkaFaktury (Invoice Footer) fields.
* **Bilingual Text:** You may issue the invoice in both English and Polish, provided the translation perfectly matches the underlying XML data submitted to KSeF.
4. **Clear the Invoice and Download the PDF**
Once you submit the invoice, KSeF will validate it in real-time.
1. Upon successful validation, the government system will assign the invoice a unique 21-character KSeF ID.
2. Your software (or the free government portal) will then allow you to download a visual representation (PDF) of the cleared XML invoice.
3. **Mandatory Check:** Before downloading, ensure the PDF visualization automatically stamps the KSeF ID and the Access QR Code onto the document. This QR code is legally required for foreign buyers to verify the invoice.
**5. Upload to Multiplier**
Because Multiplier is outside the Polish KSeF system, the invoice is not delivered to us automatically. You must log into the Multiplier platform and upload the KSeF-generated PDF (containing the QR code and KSeF ID) during the invoice creation process for your payment to be verified and processed.
### Submit the KSeF invoice
1. Log in to Multiplier using your credentials.
2. From the left sidebar, select **Payroll** > **Contractor Invoices**.
3. In the Invoices window, select **+ Create Invoice**.
4. Enter the required details in the fields given, such as Description, Start Date, End Date, Quantity, and Rate.
5. Upload your KSeF-validated invoice PDF for the relevant pay period.
6. Select Send Invoice.
6\. In the confirmation dialogue box, select Send Invoice again.
Your invoice has been submitted.
