An El Fatoora invoice is an XML file in the TEIF format with exactly one electronic signature. Tunisie TradeNet (TTN) publishes both specifications. This article summarises them in plain language, and tells you where to read the originals.
What TEIF is
TEIF stands for Tunisian Electronic Invoice Format. TTN defines it. Its implementation guide, version 2.0 dated 20 October 2021, says the format is based on the UN/EDIFACT INVOIC standard, written as XML and described by a W3C XML Schema (XSD). The guide and the XSD files are in the specification archive on TTN’s site.
The message has a header, a block for the document type and number, dates, the parties (supplier and customer), the lines, the amounts and taxes, a reference given by TTN, and a signature block. The guide marks the signature block as mandatory.
How the signature works
TTN’s document on supplier signatures (version 3.0, dated 29 May 2026) sets these rules (read it here):
- every invoice sent to El Fatoora carries a single electronic signature;
- the signature is enveloped, which means it sits inside the XML, and follows the XAdES-B standard (ETSI EN 319 132-1) with RSA-SHA256;
- the signing certificate must be issued by ANCE, the national electronic certification agency;
- the private key can be read from the Windows certificate store, from the PKCS module of a token, or from an HSM server;
- when the invoice arrives, the platform checks every digest and checks that the certificate chain is valid and not revoked, using OCSP or CRL.
Practical rules from the same document
The document ends with advice that matters to developers:
- use UTF-8 and avoid special characters;
- sign the XML in its final form, with no change afterwards;
- the signing solution must be approved by ANCE;
- every certificate that ANCE accepts is also accepted by El Fatoora, and the document names ID-Trust, Cachet Entreprise, DigiGo and Mobile ID (e-Houwiya).
It also points to the ETSI Signature Conformance Checker, an online tool, to test your signature before sending.
What the electronic seal is
A company seal is a certificate issued to a legal entity, not to a person. TunTrust describes its Enterprise-ID seal as a way to sign in the name of a legal entity, identifying the company name and tax number, to protect the integrity and authenticity of its digital documents. The uses it lists include electronic invoices and payslips. The certificate sits on an HSM and is valid for one to two years. The application form must be signed by the head of the organisation.
TTN’s specification does not require one particular certificate type. It requires one that ANCE accepts. Check with your certificate provider which product fits how your software signs.
The paper copy
Government decree no. 2016-1066 requires the issuer to hand over a paper copy of the electronic invoice on request, or when goods that are controlled on the road are transported. The copy states that it is a copy of the electronic invoice registered with the approved body under a unique reference, and carries a stamp and signature, which can be replaced by a visible electronic seal. The Ministry of Finance note of January 2026 recalls this in section I.2 (Arabic).
What this means when you build or buy
Your software must produce TEIF that validates against the current XSD, sign it exactly once in its final form, and send it. Then it must keep the reference TTN assigns. We cover the choice of software in our article on choosing software or connecting an ERP.
Questions
What is the TEIF format?
TEIF, the Tunisian Electronic Invoice Format, is the XML invoice format defined by TTN. It is based on the UN/EDIFACT INVOIC standard and described by an XSD schema published by TTN.
What signature format does El Fatoora require?
XAdES-B (ETSI EN 319 132-1), enveloped in the XML, with RSA-SHA256, and exactly one signature per invoice, according to the TTN specification version 3.0.
Who issues the certificate used to sign?
ANCE, the national electronic certification agency. TTN accepts every certificate ANCE accepts and names ID-Trust, Cachet Entreprise, DigiGo and Mobile ID.
Can I edit an invoice after signing it?
No. The TTN document says to sign the XML in its exact final form, with no later change, because the platform checks the digests.
Is the TunTrust electronic seal the same as a personal signature?
No. The Enterprise-ID seal signs in the name of a legal entity. A personal certificate identifies a person. TTN accepts the certificate types that ANCE accepts.
Sources
- TTN, Technical specifications of the electronic signature for the El Fatoora platform, version 3.0 of 29 May 2026
- TTN, El Fatoora specification archive: TEIF implementation guide v2.0 (20 October 2021) and XSD files
- TunTrust, Enterprise-ID electronic seal
- Ministry of Finance, note commune no. 2/2026, recalling decree no. 2016-1066 (Arabic only, Jibaya)
Related reading: who must issue electronic invoices, penalties and common mistakes and choosing software or connecting your ERP.
This article is general information based on the texts cited. It is not legal or tax advice. Confirm your situation with your accountant.
Axynoxia connects existing invoicing software to El Fatoora and reviews setups before go-live. See the integration service or book a discovery call. You can also open Axynoxia Invoice, our invoicing platform prepared for Tunisian electronic invoicing, at invoice.products.axynoxia.com.