Why 15th May 2026 is So Important for Taxpayers

15th May 2026 is the final due date for the 4th quarterly self-assessment (SA) tax instalment payment for the Year of Assessment 2025/2026 under the Inland Revenue Act, No. 24 of 2017.

As per the IRD instructions, the quarterly instalment due dates are:

• 15th August 2025
• 15th November 2025
• 15th February 2026
• 15th May 2026 (Final Instalment)

This makes 15th May extremely important because it is the last opportunity for taxpayers to settle their estimated income tax liability for the year through instalment payments before further tax exposures arise.

Further, taxpayers should note that a Revised Statement of Estimated Tax Payable (Revised SET) can also be submitted before 15th May 2026 if there are changes to estimated income or tax liability. The IRD instructions clearly state that a revised SET can be filed when the estimated tax payable changes from the original estimate.

Therefore, there is practically no point in submitting a revised SET after 15th May 2026, because the final instalment payment itself falls due on that date. Any revision should ideally be completed before or on 15th May to properly adjust the final tax liability and instalment payments.

Taxpayers who delay the payment beyond 15th May should also be aware of the penal provisions under the Inland Revenue Act:

• A penalty of 10% may apply if the instalment tax is not paid within 14 days from the due date.
• In addition, 1.5% interest per month or part of a month will be charged on unpaid instalments.
• Where a person willfully evades instalment payments, the law also provides for severe consequences including fines and imprisonment.

Accordingly, taxpayers are strongly encouraged to:

• Review their estimated taxable income immediately,
• Submit any necessary revised SET before 15th May 2026, and

Ensure the final quarterly instalment is paid on time to avoid penalties and interest.