When does e-invoicing become mandatory in Oman?
Under Decision 189/2026, published in Official Gazette No. 1660 on 9 August 2026, electronic tax invoices become mandatory on 1 April 2027 for taxable persons whose annual supplies exceed OMR 5 million, and on 1 October 2027 for those whose annual supplies do not exceed OMR 5 million. August to the end of October 2026 is reported as a voluntary pilot period.
What Decision 189/2026 does
Decision 189/2026 amends the Executive Regulation of Oman's VAT Law so that tax invoices must be issued electronically. It was issued on 3 August 2026 and published in the Official Gazette, issue No. 1660, on 9 August 2026. The text is available on qanoon.om, which republishes gazetted legislation.
Three elements of the decision matter most for planning. First, it fixes the dates from which electronic invoicing becomes mandatory. Second, a new Article 143 bis provides that the Oman Tax Authority (OTA) announces the companies licensed to provide e-invoicing services. Third, it places e-invoicing inside the existing VAT framework created by Royal Decree 121/2020, rather than creating a separate regime. Your VAT obligations stay the same; the way you evidence them changes.
The two mandatory dates
The decision divides taxable persons into two groups according to the value of their annual supplies:
- 1 April 2027 for taxable persons whose annual supplies exceed OMR 5 million.
- 1 October 2027 for taxable persons whose annual supplies do not exceed OMR 5 million.
The first practical question for any finance team is which side of the OMR 5 million line the business falls on. Work it out from your own supply records and confirm the reading with your tax adviser. If your turnover sits close to the threshold, plan for the earlier date. Six months separate the two groups, but neither date is far away: projects that touch an ERP, a billing system and a customer master file routinely take longer than their first estimate.
The pilot window and the older schedule
As reported by Gulf News and Forvis Mazars, August to the end of October 2026 is a voluntary pilot period in which participating businesses adopt e-invoicing ahead of the mandatory dates. Even if you are not taking part, the pilot is a useful signal of how the national system will operate in practice.
Earlier material described a four-phase rollout starting in August 2026. That includes the e-invoicing FAQ on the OTA's tax portal, which had not been updated when we last reviewed it. The FAQ predates Decision 189/2026. Where the two differ, the gazetted decision governs, so build your plan around 1 April 2027 and 1 October 2027, not around August 2026.
What changes in day-to-day invoicing
Oman's national e-invoicing programme, Fawtara, uses a five-corner model. The supplier (corner 1) sends the invoice through its e-invoicing service provider (corner 2) to the buyer's service provider (corner 3), which delivers it to the buyer (corner 4). The OTA is the fifth corner and receives the invoice data. Invoices are exchanged through service providers licensed by the OTA, so both sides of a transaction need a provider connected to the network.
The documents follow specifications published by OpenPeppol: PINT OM Billing for invoices and credit notes, PINT OM Self-Billing for self-billing transactions, and the Oman Tax Data Document, which carries the data reported to the tax authority. All use the UBL 2.1 syntax. Our Peppol explainer shows how the pieces fit together.
For a finance team, the shift is that an invoice stops being a document you lay out and send yourself and becomes structured data that has to pass validation before it travels. Missing buyer details, inconsistent tax categories or credit notes that do not point to an original invoice will be caught before the document reaches your customer, not weeks later in a dispute.
How to use the months before your date
- Confirm your group. Establish whether your annual supplies exceed OMR 5 million.
- Map your invoice sources. List every system that issues invoices, credit notes or debit notes, including spreadsheets.
- Clean your master data. Customer VAT numbers, addresses and item tax categories are the most common causes of rejected documents.
- Choose a service provider. Check the OTA's own published list of licensed providers before you commit.
- Test real scenarios. Run invoices, credit notes and any self-billing flows end to end well before your date.
Our Oman e-invoicing guide expands on each step, and the e-invoicing feature page explains how Invoice And Tax checks every document against versioned, deterministic rules and Schematron conformance checks before transmission.
| Period | Who it applies to | Status |
|---|---|---|
| August to end of October 2026 | Participating businesses | Voluntary pilot (as reported) |
| From 1 April 2027 | Taxable persons with annual supplies above OMR 5 million | Mandatory |
| From 1 October 2027 | Taxable persons with annual supplies of OMR 5 million or less | Mandatory |
Questions about the timeline
Does e-invoicing become mandatory in 2026?
No. The mandatory dates in Decision 189/2026 are 1 April 2027 and 1 October 2027. August to the end of October 2026 is reported as a voluntary pilot period.
Is the four-phase schedule on the OTA FAQ still current?
That FAQ predates Decision 189/2026. The gazetted decision sets the current dates, so plan around them and treat older phase descriptions as superseded.
How can I tell whether a service provider is licensed?
Under Article 143 bis, the OTA announces the companies licensed to provide e-invoicing services. Rely on the OTA's own list rather than on any provider's description of itself.