Before you set up eInvoicing, take a moment to check what your country actually requires. Small details like the wrong identifier, missing address fields, or an unsupported file format can block invoice delivery or cause issues with tax reporting.
Read this article to review what applies to your location so you can configure eInvoicing correctly from the start and ensure it works as expected.
Before you start
eInvoicing in Belgium
If you operate in Belgium:
We recommend using the Company Registration Number (KBO/CBE) as the identifier.
For example, when setting up eInvoicing, select:
Identifier Type: KBO/CBE
Registration Number: [KBO/CBE Number]
If only a VAT number is available, that can still be used, but the registration number provides better compatibility.
eInvoicing in Italy (SDI)
If you operate in Italy, your eInvoicing and tax reporting will be handled together through the SDI (Sistema di Interscambio).
Additionally, please keep in mind the following requirements:
Every recipient company must include an address, city, and postcode; otherwise, invoice delivery will fail.
The names of the Billing Plans for which you issue invoices must contain only letters, numbers, and the special characters from the Basic Latin Unicode block.
eInvoicing in Spain (VeriFactu)
If you operate in Spain, your tax reporting will run through VeriFactu as follows:
An invoice is generated.
A QR code is generated.
A PDF of the invoice is generated, and the QR code is added to it.
The invoice is sent to the customer.
eInvoicing in Poland (KSeF)
If you operate in Poland, you must use Krajowy System e-Faktur (KSeF). This is Poland's mandatory National e-Invoicing System.
You must also upload your KSeF certificate and enter the certificate PIN when configuring eInvoicing in your organization.
Supported file formats for KSeF
KSeF requires a .p12 or a .pfx file because it needs the private key to sign the invoice XML before submitting it to the Krajowa Administracja Skarbowa. A .crt alone can't sign anything.
The .p12 and .pfx files contain the full certificate bundle: public certification + private key + optionally the CA chain, password-protected.
If you download the certificate from KSeF in a .crt file, you cannot upload it to OfficeRnD Flex. As mentioned, there is a difference between the two file types:
.crt – Contains only the public certificate (no private key)
.p12 and .pfx – Contains the full certificate bundle: public certificate + private key + optionally the CA chain, password-protected
You will receive the following error when you upload a .crt file: "Only .p12 and .pfx certificate files are allowed".
What to do: Get the .p12 or .pfx file from whoever issued the certificate – it's usually provided alongside the .crt at the time of issuance, or needs to be exported from the certificate store. Alternatively, convert the .crt file:
Convert a .crt file to a .p12 or .pfx file
To convert a .crt file to a .p12 or a .pfx file:
.crt (certificate)
.key (private key)
With these two, you can generate a .p12 file using OpenSSL:
openssl pkcs12 -export \
-out certificate.p12 \
-inkey private.key \
-in certificate.crt
This will prompt for a password (later needed for the .p12 file).
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