Oman income tax filing deadline and audited accounts requirement

15 March 2026

Oman Income Tax Filing Deadlines and Audit Requirements

Businesses in Oman must submit their annual income tax returns electronically within the deadlines set by the Income Tax Law and Oman Tax Authority guidance. For taxpayers with a financial year ending on 31 December, small enterprises subject to 3% income tax generally file by 30 March, while companies subject to the standard 15% income tax rate generally file by 30 April.

The deadline is not only a tax-payment date. It is also the date by which the correct return form, supporting accounts, and tax payment should be submitted through the Oman Tax Authority portal. Missing the deadline may create penalties even where the business has little profit, no profit, or qualifies for certain small-enterprise tax treatment.

Key filing deadlines

The Oman Tax Authority explains that taxpayers subject to 3% should submit the return before the expiry of three months from the end of the tax year. Taxpayers subject to 15% should submit the return before the expiry of four months from the end of the tax year. For a 31 December year-end, this means:

30 March for eligible small enterprises taxed at 3%.
30 April for companies and establishments taxed at 15%.
Different accounting year-ends should calculate the deadline based on three or four months from the end of the approved tax year or accounting period.

Small enterprises: 3% return and no audit requirement

Small enterprises that fall under the 3% income tax regime are still required to submit an income tax return. However, the filing is simplified. The Tax Authority guidance states that establishments subject to 3% should submit the return including gross income and expenses. Audited financial statements are not required in the same way as for 15% taxpayers.

To qualify as a small enterprise subject to the 3% rate, the Tax Authority FAQ describes conditions that include registered capital not exceeding OMR 60,000, annual gross income not exceeding OMR 150,000, not more than 25 workers, and the activity not being an occupational activity. Businesses should check their position every year, because crossing the conditions may move the taxpayer into the standard 15% regime.

Taxpayer category	Typical deadline for 31 December year-end	What to submit
Small enterprise taxed at 3%	30 March	Income tax return with gross income and expenses. Audited accounts are generally not required for the 3% small-enterprise return.
Company or establishment taxed at 15%	30 April	Income tax return with audited accounts attached.
Businesses with a different approved year-end	Based on tax year or accounting period end	Apply the three-month or four-month rule depending on the tax category.

15% companies: audited accounts required

Companies and establishments taxed at the standard 15% rate must submit the income tax return with audited accounts. The audited financial statements should be prepared and signed by an auditor registered in Oman, and the tax return should reconcile taxable income with the accounting records.

This is why the income tax filing process should begin before the last week of April. Management usually needs time to close books, complete audit schedules, confirm related-party balances, review withholding tax and VAT positions, and make final tax adjustments before submission.

Filing is required even if profit is low

The Tax Authority FAQ states that income tax applies to commercial registrations and that all CR holders must register for income tax. A Riyada card, small-enterprise treatment, low profit, or business losses should not be treated as a reason to ignore the filing obligation. Certain small enterprises may be exempt from tax, but not from submitting the return.

Penalties for late or incorrect filing

Late income tax filing can create avoidable costs. Under Oman Income Tax Law and Tax Authority guidance, failure to submit the income tax return within the required deadline may result in an administrative penalty from OMR 100 up to OMR 2,000. Where tax remains unpaid after the due date, an additional tax of 1% per month may apply on the unpaid tax due and payable.

Incorrect income declarations can also create exposure. The Income Tax Law allows a penalty for incorrect income declaration calculated by reference to the difference between tax on the correct taxable income and tax as per the submitted return. Proper books, supporting invoices, bank reconciliations, and tax schedules are therefore essential before filing.

Practical checklist before filing

Confirm whether the business is taxed at 3% or 15% for the relevant year.
Check whether the 31 December year-end applies or whether another approved accounting period is used.
For 3% small enterprises, prepare gross income and expense details with supporting records.
For 15% companies, complete the audit and attach audited accounts to the return.
Reconcile accounting profit to taxable income and review disallowable expenses, depreciation, losses, and withholding tax matters.
Submit the return electronically through the Oman Tax Authority portal and pay any tax due by the deadline.

How Al Osool can help

Al Osool supports businesses in Oman with income tax return filing, small-enterprise return preparation, audited financial statements, tax computations, penalty-risk review, and submission support through the Oman Tax Authority portal. Our team helps businesses prepare accurate returns and reduce last-minute filing pressure.

For support with income tax filing in Oman, visit our Taxation-Related Services page or contact Al Osool.

Official references

This article is for general information only and should not be treated as legal or tax advice for a specific transaction. Businesses should seek professional advice based on their activities, registration status, and documentation.