Oman to introduce mandatory E-invoicing from April 2027

The new legislation represents a significant change to the way tax invoices are issued, exchanged and stored in Oman, with businesses expected to transition from traditional invoice formats to a secure electronic invoicing framework.

What does the decision require?

Under Decision No. 189/2026, taxpayers will be required to issue tax invoices in an approved and secure electronic format that ensures the integrity, security and proper storage of invoice data. Invoices will be generated in XML format and exchanged through electronic invoicing service providers accredited by the Oman Tax Authority. The framework is intended to enable invoice data to be read, validated and processed electronically.

Each invoice will also be assigned a unique invoice number. Once the amended requirements take effect, paper invoices, PDF invoices and digital images of invoices sent by email will no longer satisfy the legal definition of a tax invoice. Businesses that currently rely on these formats will therefore need to consider how their existing invoicing processes and systems will need to change.

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Phased implementation

The mandatory requirements will be introduced in two phases:

• 1 April 2027

  Taxpayers whose annual value of supplies exceeds OMR 5 million.

• 1 October 2027

  Taxpayers whose annual value of supplies does not exceed OMR 5 million.

Ahead of mandatory implementation, the Oman Tax Authority has opened a voluntary adoption period from August through to the end of October 2026. This period provides taxpayers with an opportunity to begin implementing e-invoicing, test their systems and assess their readiness ahead of the mandatory rollout.

What should businesses consider?

The transition to e-invoicing will require businesses to consider the impact on their existing systems, processes and controls.

In particular, businesses should consider:

• Whether their existing invoicing systems can generate invoices in the required XML format
• How invoices will be exchanged through an accredited electronic invoicing service provider
• How invoice data will be validated, transmitted and securely stored
• How existing manual invoicing processes will be affected by increased system-to-system exchange
• Whether appropriate controls are in place to maintain the integrity and security of invoice data
• The time required to test and implement any necessary system or process changes

Businesses approaching or exceeding the OMR 5 million threshold should particularly consider their readiness ahead of the 1 April 2027 implementation date.

Preparing for the transition

With the voluntary adoption period now underway, businesses have an opportunity to assess their current invoicing arrangements and identify areas requiring attention. Early preparation could include reviewing existing invoicing processes, assessing system capabilities, considering the requirements for integration with an accredited service provider and testing systems before the applicable mandatory deadline.

The Oman Tax Authority is also expected to issue further technical guidance and announcements as implementation progresses. Businesses should continue to monitor these developments and consider their potential impact on implementation plans.

How Forvis Mazars can help

Forvis Mazars is closely monitoring developments relating to e-invoicing and further guidance from the Oman Tax Authority. Our team can assist businesses in assessing their readiness, reviewing current invoicing processes and identifying the steps required to prepare for the new requirements.

We would be pleased to discuss how the introduction of e-invoicing may affect your business and what actions you may wish to consider ahead of the applicable implementation date.

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