Oman E-Invoicing Data Dictionary: Business Terms, Rules & Code List Introduction

The Oman e-invoicing data dictionary is the rulebook for Fawtara. Every invoice issued from August 2026 will be tested against it. The Oman Tax Authority (OTA) released the first draft in December 2025. It sets out what data each invoice must carry, how it is validated, and which standardised codes apply. Read it before your ERP team does.

Note: The data dictionary is currently in public consultation as v1.0.1. All figures and specifications in this article reflect the draft version and are subject to change before the OTA publishes the final specification. Monitor tms.taxoman.gov.om/portal/e-invoicing for updates.

Key Takeaways

• The Oman e-invoicing data dictionary has three layers: business terms, business rules and code lists.
• Version 1.0.1 contains 336 business rules and 17 code lists governing every field on a Fawtara-compliant invoice.
• A standard tax e-invoice needs 53 mandatory data fields, with 66 conditional fields depending on the transaction.
• Simplified tax invoices need 46 mandatory fields, and 50 conditional fields.
• Eight document types and fourteen transaction types are in scope under Fawtara.

What is the E-Invoicing Data Dictionary in Oman?

The e-invoicing data dictionary is the technical specification published by the Oman Tax Authority (OTA) defining every data element required on a Fawtara-compliant electronic invoice.

In plain terms, it tells you what to include in an invoice, how it must be formatted, and what values are allowed.

The OTA released the first version (v1.0.1) of the Oman e-invoicing data dictionary in December 2025 for public consultation. It was shared first with the ~150 large taxpayers selected for Phase 1, and then with prospective Accredited Service Providers (ASPs).

The dictionary broadly aligns with the PEPPOL 5-corner model and the PINT-OM specification (Peppol International NUNG — Oman profile), based on UBL 2.1. But it is not a copy-paste of PEPPOL. The OTA has added Oman-specific requirements covering import transactions, profit-margin invoicing, self-billed invoices for imports, and QR code and digital signature rules for simplified invoices.

Three terms come up repeatedly: business terms, business rules and code lists. Each does a different job, and your ERP needs to handle all three.

Oman E-Invoicing Business Terms

Business terms (BT) are the actual data fields on an e-invoice. Each business term has two attributes that matter. 

• The e-invoicing business term name is the descriptive label (for example, "Invoice issue date"). 
• The e-invoicing business term ID is the technical reference your service provider's validation engine actually reads (for example, "BT-2").

The Oman e-invoicing business terms fall into two groups. Standard EN16931 fields are inherited from the European norm and prefixed BT. And Oman-specific fields, prefixed BT-OM.

A standard tax e-invoice carries 53 mandatory fields, with another 66 that become mandatory under certain conditions. A simplified tax invoice has 46 mandatory fields and 50 conditional fields. Today, an Oman VAT tax invoice contains about 18 to 20 fields. That is the gap finance and IT teams have to close before Phase 1 goes live.

Oman E-Invoicing Business Rules

Business rules (BR) are validations applied to the business terms. They enforce data formats, conditional logic, calculation accuracy and cross-field checks.

The version 1.0.1 contains 336 OMAN e-invoicing business rules, organised across five categories:

• Field presence and format rules: To mandate that required fields exist and conform to the correct data type, length, and format (date, decimal precision, string pattern).
• Conditional logic rules: To activate additional field requirements depending on the invoice type, document type, or VAT category in use.
• Calculation accuracy rules: To verify the line totals, VAT amounts, and invoice totals are arithmetically consistent with each other.
• Code list compliance rules: To confirm that values entered in coded fields (invoice type, currency, country, VAT category) are drawn exclusively from the OTA-approved lists.
• Cross-field consistency rules: To validate that combinations of fields are coherent. For example, a zero-rated line must carry a structured reason code, and a special-zone invoice must include the correct zone flag.

Two practical points follow from this:

1. Your ERP cannot just produce data. It has to produce valid data. The rules will reject an invoice that calculates correctly but uses a wrong country code, or carries a future-dated invoice date.
2. An error caught at the access point is materially cheaper than one flagged by the OTA after submission. This pattern has repeated across the Kingdom of Saudi Arabia (KSA) and India.Teams that build validations into their own systems spend less time on rejections later.

Oman E-Invoicing Codes List

The OMAN e-invoicing codes list is a set of standardised values the OTA will accept for specific fields. Version 1.0.1 carries 17 code lists. The most important ones are below.

1. Invoice Type Codes List: 

The e-invoicing invoice type codes for Oman are drawn from UN/CEFACT code list 1001. The OTA has restricted the values to document types supported under Fawtara.

2. Currency Codes List: 

The e-invoicing currency codes in Oman follow ISO 4217. Domestic invoices must use OMR. You can raise an invoice in any non-OMR currency for a cross-border supply. But VAT has to be reported in OMR. The OTA expects the tax currency on the invoice to be set as OMR, with amounts converted using the official exchange rate.

3. Country Codes List: 

The e-invoicing country codes use ISO 3166-1 alpha-2. Two letters. No country names, no custom codes. These codes apply to the seller address, buyer address, country of origin for goods, and the delivery address fields. A wrong code will fail validation before the invoice reaches the buyer.

4. VAT Category Codes List: 

VAT category codes follow EN16931 standards used across PEPPOL. The OTA has restricted them to the categories that exist under Oman VAT law.

A separate reason code list applies on top of these. For example, a "Z" line will not be accepted on its own. The invoice must carry the basis for zero-rating, picked from the OTA's reason codes. The same applies for exempt supplies and for zero-rated export of services, where additional detail on the nature of the service is required.

This is one of the bigger operational changes from the current Oman VAT system. Today, a "zero-rated" classification on the invoice is enough. Under Fawtara, you have to back it with a structured reason.

What this means for your business

Phase 1 of Oman e-Invoicing (Fawtara) begins in August 2026. The compliance gap is wider than most teams think. The OMAN e-invoicing data dictionary turns invoice creation into a structured data problem, not a document problem. PDFs and emailed invoices will stop being valid for in-scope businesses.

Across GCC e-invoicing implementations, three areas consistently fail first.

1. Master data quality: Customer and supplier records often miss the postal code, an active VAT number, or the right country code. These will fail validations on day one.
2. ERP field availability: Most ERPs do not natively carry fields like Invoice UUID, invoice hash, line-level VAT split, or zone codes. Extension fields or middleware are needed.
3. VAT classification: Sales and finance teams classify supplies loosely today. The data dictionary forces a strict, structured code on every single line.

How ClearTax Addresses Oman e-Invoicing Gaps

ClearTax supports businesses across the GCC in each of the three areas above.

• Master data quality: A field-by-field audit of customer and supplier records against the PINT-OM requirements before invoice generation begins surfacing missing postal codes, inactive VAT numbers, and incorrect country codes before they cause day-one rejections.
• ERP readiness: Full mapping of Oman data dictionary, including the BT-OM Oman-specific fields against existing ERP outputs and identifies exactly which fields are absent or incorrectly formatted.
• VAT classification: Validation that every supply line carries the correct category code and, where required, a structured reason code from the OTA-approved list.

Also, ClearTax runs pre-submission validations for the full set of 336 business rules before invoices reach the OTA access point, catching errors internally rather than in production. If your business is in Phase 1 or Phase 2 of the Fawtara rollout, the time to start is now.