Sri Lanka Tax Deadline Calendar — IRD Due Dates 2026

This calendar reproduces the statutory due dates published by the Inland Revenue Department (IRD) in its official Tax Calendar 2026 — Last Dates for Making Payments & Filing Returns, cross-read line by line against the Acts that create each obligation. It does not estimate anything: every date is fixed by law, and the only value the tool computes is the number of whole calendar days between your as-of date and each due date.

The rules it applies, verbatim from the IRD calendar:

• Income tax installments — quarterly self-assessment payments on 15 August and 15 November of the year of assessment, then 15 February and 15 May of the following year (Inland Revenue Act No. 24 of 2017).
• Income tax final payment — the balance for a year of assessment is due 30 September following the year end.
• Income tax annual return — on or before 30 November following the end of the year of assessment.
• VAT — payment by the 20th of the month after the taxable period; the return is filed by the last day of that month (monthly filers) or the last day of the month after the quarter end (quarterly filers), under the VAT Act No. 14 of 2002.
• SSCL — monthly payment by the 20th of the following month, with a quarterly return by the 20th after the quarter end (Social Security Contribution Levy Act No. 25 of 2022).
• APIT (PAYE) and WHT/AIT — amounts deducted in a month are remitted by the 15th of the following month, with an annual employer/agent statement due 30 April after the year of assessment.

A Sri Lankan year of assessment runs 1 April to 31 March, so a single calendar contains obligations for two overlapping assessment years — the installments of the current year and the final payment plus return of the one just ended. The tool works out which occurrence of each rule comes next on or after your chosen date, and rolls forward automatically once a date has passed.

Day counting uses a serial-day-number algorithm (Howard Hinnant's days-from-civil), which is pure integer arithmetic with no reliance on the system clock or timezone, so a countdown never drifts by a day across daylight-saving or UTC boundaries. A second, independent calculation using UTC midnights cross-checks every result — the two must agree to the day. Penalty and interest figures are deliberately left out, because those rates change and a wrong rupee figure would be worse than none; the tool only flags that a missed date attracts penalties and links you to the IRD.

• IRD — Tax Calendar 2026 (Last Dates for Making Payments & Filing Returns) [PDF]
• IRD — Tax Calendar (official landing page)
• IRD — Inland Revenue Act No. 24 of 2017, VAT Act No. 14 of 2002, SSCL Act No. 25 of 2022
• Inland Revenue Department of Sri Lanka — official site

Every due-date rule on this page was cross-checked against the IRD Tax Calendar 2026 on 2026-07-10. The calendar is reviewed each January when the IRD publishes the new year's edition, and whenever an Inland Revenue, VAT or SSCL amendment changes a due date.