Most Singapore companies must file Estimated Chargeable Income (ECI) within three months after their financial year-end. The usual filing waiver requires both annual revenue of S$5 million or below and nil ECI; IRAS also specifies some other exempt categories. Late filing can lead to an estimated assessment. Eligible Singapore-registered companies on GIRO may obtain up to ten interest-free instalments by filing early.

Here is what that means for your business, in plain terms.

What ECI is (and how it differs from Form C-S/C)

ECI is your company’s early estimate of its taxable income for a financial year. You file it before your full accounts are finalised, using your management figures. It is separate from your annual Corporate Income Tax Return (Form C-S, Form C-S (Lite) or Form C), which is due by 30 November. Think of ECI as the early heads-up and the Form C-S/C as the final word.

When is ECI due?

Generally, within three months from the end of your financial year — and the clock runs off your financial year-end, not the calendar year. So:

  • Financial year-end 31 December → ECI due 31 March
  • Financial year-end 31 March → ECI due 30 June
  • Financial year-end 30 June → ECI due 30 September

IRAS usually sends a filing notification in the last month of your financial year. Important: if the reminder does not arrive and you do not qualify for the waiver, you must still file on time.

Who is exempt — the ECI filing waiver

You do not need to file ECI for a Year of Assessment when both of these are true:

  1. Your annual revenue is S$5 million or below for the financial year; and
  2. Your ECI is nil for the Year of Assessment (measured before deducting the start-up or partial tax exemption).

Meeting only one condition is insufficient for the usual ECI filing waiver. Unless a separate IRAS exemption applies, a company with revenue above S$5 million and nil ECI must still file. Companies that meet both waiver conditions self-assess and need not notify IRAS. The annual Form C-S, Form C-S (Lite) or Form C obligation is separate and still applies unless IRAS has granted the relevant return-filing waiver.

What happens if you file late

If required ECI is not filed on time, IRAS may issue an estimated Notice of Assessment (NOA). An objection generally has to be filed within two months of the NOA date; the assessment generally remains payable while it is reviewed. If you actually qualify for the ECI waiver but receive an estimated NOA, contact IRAS via myTax Mail before the payment due date so the assessment can be checked.

Filing early can smooth your cash flow

Here is the upside most SMEs overlook. If your company is Singapore-registered and on GIRO, the number of interest-free instalments you get depends on how early you file:

  • File by the 26th of the 1st month from your financial year-end → up to 10 instalments
  • File by the 26th of the 2nd month → up to 8 instalments
  • File by the 26th of the 3rd month → up to 6 instalments
  • File after the 26th of the 3rd month → no instalments (pay in full)

If you do not already have a GIRO arrangement for Corporate Tax, apply early — GIRO must be approved before the payment due date for you to enjoy instalments.

A simple checklist for your ECI

  1. Confirm your exact financial year-end and count three months forward.
  2. Close enough of your accounts to estimate taxable profit for the year.
  3. Test the two waiver conditions separately — revenue and nil ECI.
  4. If filing, aim for the 26th of month one, two or three to keep more instalments.
  5. e-File via myTax Portal (mytax.iras.gov.sg) using Corppass, and save the acknowledgement.

Subject to your company’s facts, getting ECI right is usually straightforward once your bookkeeping is current — which is exactly why a clean, up-to-date set of books pays off at year-end.

Speak with BTA

Not sure whether the waiver applies to you, or want your ECI and instalment timing handled properly? Speak with BTA to review your position — we help Singapore SMEs keep their corporate tax compliance accurate and on time, and keep your accounts and bookkeeping ready for filing.

Call +65 6539 9248 · businesstaxaccountancy.com.sg

Source: IRAS ECI filing guidance. The instalment plan is subject to eligibility and the minimum monthly GIRO amount; filing by the 26th matters even if the statutory ECI deadline falls later in that month.

Reviewed and updated on 24 October 2026. General information only; requirements depend on your circumstances and current official guidance.