Estimated Chargeable Income (ECI) is your company's early estimate of taxable profit, filed with IRAS within three months of your financial year-end. You may be waived from filing only if annual revenue is S$5 million or below and ECI is nil — both must hold. Filing early (by the 26th of the first month after year-end) secures up to ten monthly GIRO instalments; filing late forfeits instalments and risks an estimated assessment. The full Form C-S or Form C is still due by 30 November regardless.
Who this matters to
- Directors and finance staff of any active Singapore private limited company with a corporate tax obligation.
- New companies approaching their first financial year-end and first ECI deadline.
- Owner-managed businesses near the S$5 million revenue line, where the filing waiver is easy to misread.
- Companies on GIRO that want to spread their tax payment across the year through instalments.
Every Singapore company faces two annual corporate tax filings with IRAS: the Estimated Chargeable Income filing and the full Form C-S or Form C return. ECI filing comes first, due within three months of your financial year-end, and getting it wrong can lock you out of instalment payment and trigger estimated assessments.
What Estimated Chargeable Income means
Estimated Chargeable Income is your company's estimate of its taxable profit—revenue less tax-allowable expenses and capital allowances—for a Year of Assessment. It is not net accounting profit; you must adjust for non-deductible items such as fines, depreciation, and private-car expenses.
IRAS uses your ECI to calculate an early tax assessment and, for companies on GIRO, to set up monthly instalments. You file the formal return (Form C-S, Form C-S (Lite), or Form C) months later, by 30 November, but the ECI gives IRAS—and your company—a provisional tax figure early.
Important: Report ECI before deducting the partial tax exemption or start-up tax exemption. IRAS applies those reliefs automatically when it computes your tax payable. For example, if your adjusted profit is $150,000, file $150,000 as your ECI even though the first $200,000 enjoys partial exemption; the Notice of Assessment will reflect the lower effective rate.
The three-month filing deadline
Your company must file ECI within three months from the end of its financial year. A company with a 31 December 2025 year-end must file by 31 March 2026; a 30 June 2025 year-end triggers a 30 September 2025 deadline.
IRAS sends a notification in the last month of your financial year, but the obligation exists whether or not you receive it. New companies that close their first accounts in the year of incorporation—rare but possible—must file within three months of that first year-end, even without a notification.
Miss the three-month window and your company loses the right to instalment payment. IRAS may also issue an estimated Notice of Assessment based on prior years or other information, demanding full payment within one month and imposing late-payment penalties if you do not pay.
The revenue-and-nil-ECI waiver most owners misread
Your company qualifies for an ECI filing waiver if both of these conditions hold:
- Annual revenue for the financial year does not exceed S$5 million; and
- Estimated Chargeable Income for the Year of Assessment is nil.
Revenue means your main source of income (trading turnover for an operating company, investment income for a holding company) and excludes separate-source items such as interest, dividends, or rental income that do not arise from the principal activity. ECI is nil when your taxable profit—after all deductions, allowances, and loss set-offs—is zero or negative.
Many owners misread the rule. A company with S$3 million revenue and a small profit of S$10,000 must still file; the waiver applies only when both tests pass. Conversely, a company with S$6 million revenue and nil profit must file a nil return because revenue exceeds the threshold. If your company qualifies for the waiver, you do not file ECI for that Year of Assessment—even if the myTax Portal shows "Ready to File"—and you do not need to contact IRAS for confirmation.
Remember that the ECI waiver is separate from the annual Form C-S or Form C filing. Even if you skip ECI under the waiver, you must still file the full return by 30 November.
What happens if IRAS issues an assessment despite the waiver
If your company qualifies for the waiver but receives a Notice of Assessment, write in via myTax Mail before the payment due date, confirming that annual revenue was S$5 million or below and ECI was nil. IRAS will amend the assessment and will not pursue payment or penalties.
The early-filing instalment advantage
Singapore-registered companies on GIRO that file ECI within three months enjoy instalment payment of the estimated tax. The earlier you file, the more instalments IRAS grants, spreading cashflow over the year.
File by the 26th of the first, second, or third month after your financial year-end to secure up to ten, eight, or six monthly instalments respectively. For a 31 December year-end, filing by 26 January yields ten instalments; filing by 26 February gives eight; filing by 26 March offers six. Each instalment is deducted via GIRO on the 6th of the month, subject to a minimum deduction of S$50 per month.
To qualify, your company must have an approved GIRO arrangement before the payment due date (one month from the Notice of Assessment). Sign up for GIRO at least three weeks before filing ECI to ensure approval in time. Companies that file late—after three months—or that are not on GIRO must pay the full estimated tax within one month, with no instalment option.
This instalment perk is valuable for managing working capital: a S$20,000 tax bill paid over ten months is easier to absorb than a lump sum. Early filing also signals orderly books to IRAS, reducing the likelihood of compliance reviews.
What business owners should do
- Close your monthly management accounts within a few weeks of year-end so you can compute ECI accurately and file early for maximum instalments.
- Check both waiver conditions—revenue ≤ S$5 million and nil ECI—before deciding to skip filing; when in doubt, file a nil return.
- Set up or confirm your GIRO arrangement at least three weeks before your ECI filing date to secure instalment payment.
- Diarise the three-month deadline from your financial year-end and the 26th-of-the-month cut-offs for instalment tiers.
- Reconcile your ECI figure with your year-end draft accounts to avoid large discrepancies when you file Form C-S later, which can prompt IRAS queries.
Our accounting and tax team helps Singapore companies prepare timely ECI computations, manage IRAS filing calendars, and optimise cashflow through early filing and instalment arrangements. See how we handle corporate tax filing in Singapore end to end. If you need support with corporate tax compliance—including ECI, Form C-S, transfer-pricing documentation, or audit defence—reach out through our contact page and we will tailor a solution for your business.
Treat ECI as a deadline you control: close your books early, check both waiver tests carefully, and file by the 26th of the first month after year-end to secure ten instalments and keep IRAS assessments predictable. Early discipline on ECI frees up cashflow and reduces compliance risk for the rest of the year.
Common mistakes
- Assuming the waiver applies on revenue alone — both tests (revenue ≤ S$5 million and nil ECI) must be met.
- Reporting ECI after the partial or start-up exemption, instead of before — IRAS applies those reliefs itself.
- Waiting for an IRAS notification before acting — the three-month obligation stands even if none arrives.
- Leaving GIRO sign-up too late, so instalment payment isn't approved before the payment due date.
- Filing an ECI figure that later differs sharply from the Form C-S, which can prompt IRAS queries.
Frequently asked questions
When is ECI due in Singapore?
A company must file its Estimated Chargeable Income within three months of its financial year-end. For a 31 December 2025 year-end, ECI is due by 31 March 2026. The obligation applies whether or not IRAS sends a notification.
Who qualifies for the ECI filing waiver?
A company is waived from filing ECI only if both conditions are met for the year: annual revenue does not exceed S$5 million, and the Estimated Chargeable Income is nil. If only one condition is met, you must still file. The full Form C-S or Form C is still required by 30 November.
Should I report ECI before or after tax exemptions?
Report ECI before deducting the partial tax exemption or start-up tax exemption. IRAS applies those reliefs automatically when it computes your tax payable, so the Notice of Assessment reflects the lower effective rate.
What happens if I miss the ECI deadline?
You lose the right to pay the estimated tax by instalments. IRAS may also issue an estimated Notice of Assessment based on prior years, demanding full payment within one month, with late-payment penalties if you do not pay.
How does early ECI filing help cashflow?
Companies on GIRO that file early get more monthly instalments. Filing by the 26th of the first, second or third month after year-end secures up to ten, eight or six instalments respectively, spreading the tax payment across the year.
I qualify for the waiver but received a Notice of Assessment — what do I do?
Write in via myTax Mail before the payment due date, confirming that annual revenue was S$5 million or below and ECI was nil. IRAS will amend the assessment and will not pursue payment or penalties.