Oman e-invoicing data dictionary (Fawtara): a technical guide

Oman's Fawtara e-invoicing programme is built on a detailed technical specification — the e-invoicing data dictionary — which defines exactly what every electronic invoice must contain. Based on the UBL 2.1 standard, it sets out 200+ business terms, validation rules and code lists. This guide breaks down the key parts so you know what your systems must produce.

Built on UBL 2.1

The Oman data dictionary follows UBL 2.1 (Universal Business Language), the internationally recognised format also used by Peppol. Invoices must be issued as structured XML (or JSON), not PDFs, so they can be validated automatically before transmission.

How the dictionary is structured

BT-XXX — Business Terms (individual fields, e.g. the invoice number).
BG-XXX — Business Groups (groups of related fields, e.g. seller details).
BR-XXX — Business Rules (validation checks each invoice must pass).
CL-XXX — Code Lists (allowed values, e.g. tax category codes).
Oman-specific fields carry an OM marker (e.g. BT-OM-1).

Core invoice header fields

BT-1 — Invoice number: a unique identifier, 1–50 characters, mandatory.
BT-OM-1 — Transaction type: a 20-digit code flagging scenarios such as imports, exports and reverse charge (RCM).
BT-OM-14 — QR code: mandatory, base64-encoded.
BT-OM-28 — Digital signature: XAdES-based, guaranteeing authenticity and integrity.

Seller and buyer details

A mandatory VAT Identification Number (VATIN) in the format OM + 12 digits.
A full postal address (up to three lines plus PO Box, city and zone code).
An electronic address (EndpointID) with a scheme such as VATIN, used for Peppol routing.

Line items, tax and totals

BT-129 — Invoiced quantity, using standard unit codes.
VAT category codes: S (standard 5%), E (exempt), Z (zero-rated), O (out of scope).
Totals: tax-exclusive amount (BT-109), tax-inclusive amount (BT-112) and amount payable (BT-115).

Validation rules enforce all of this — for example, BR-OM-03 requires a correctly formatted VATIN, and BR-22 requires a quantity on each line. Invoices that fail any rule are rejected before they reach the tax authority.

Supported document types

The specification covers tax invoices, credit and debit notes, and simplified variants for B2C/POS.

How the 5-Corner flow works

The seller's system sends the invoice to its accredited service provider (Corner 1).
The seller's provider transmits it over Peppol to the buyer's provider (Corners 2–3).
The buyer receives a validated invoice (Corner 4).
The OTA's Fawtara platform receives the data in real time (Corner 5).

Your readiness checklist

Assign technical and administrative contacts for the project.
Check whether your ERP/POS can produce UBL 2.1 structured invoices.
Plan QR-code and XAdES digital-signature generation.
Select an OTA-accredited service provider (ASP).
Train your finance and IT staff on the new requirements.

How WITSOLS helps

We map your Odoo or ERPNext data to the Oman data dictionary, set up structured XML/JSON output, QR codes and digital signatures, and integrate with an accredited service provider — so your invoices pass validation first time. Get an assessment, and read our overview of the Fawtara e-invoicing mandate.