Within 3 months of your company's financial year end. A 31 December year end means ECI is due by 31 March.

Who is exempt from filing ECI?

Companies that meet BOTH conditions: annual revenue of S$5 million or less for the financial year, AND ECI of nil (before the exempt amount) for the Year of Assessment. Meet both and you simply don't file — no application needed.

What if my ECI turns out different from my actual tax return?

That's expected — ECI is an estimate. IRAS assesses the difference when you file Form C-S/C by 30 November. A significantly understated ECI without good reason can attract questions, so estimate honestly from your books.

ECI filing in Singapore: the deadline, the waiver, and how to estimate it

ECI (Estimated Chargeable Income) is a quick estimate of your company's taxable profit that IRAS wants within 3 months of your financial year end — months before the actual tax return is due. Year ended 31 December? ECI by 31 March. Year ended 30 June? ECI by 30 September.

The waiver most small companies qualify for

You do not need to file ECI if — for that year — both are true:

Annual revenue is S$5 million or below, and
ECI is nil (you made a tax loss, or exemptions wipe the estimate to zero — measured before the exempt amount).

Profitable small companies do file ECI — the waiver needs both legs. There's no form for the waiver itself; if you qualify, you simply don't file.

Why filing early is actually good for cash flow

File ECI within the first month after year end and pay by GIRO, and IRAS spreads the tax over up to 10 monthly instalments. File in month two and you get fewer; month three, fewer still. Wait for the Notice of Assessment instead and it's one lump sum within a month.

How to estimate it

ECI is your accounting profit with the usual tax adjustments — add back depreciation and non-deductibles, deduct capital allowances — before the exempt amount. If your books are current, it's a ten-minute job. Remember ECI doesn't replace the return: Form C-S is still due 30 November.

Books current = ECI free: Bookly keeps your profit figure live all year and prepares the IRAS-format computation, so the ECI number is just… there. Estimate your tax now or start free.

Per IRAS rules as at June 2026. General information, not tax advice — confirm your company's position on iras.gov.sg.