Full Filing Timeline
Estimate your income tax before you file.
Use the Income Tax Calculator →Understanding ECI — Singapore's Unique Self-Assessment Step
Estimated Chargeable Income (ECI) is a distinctly Singaporean requirement: companies must estimate their own taxable income for the financial year and file it within 3 months of that year ending — well before the full Corporate Tax return is even due. This gives IRAS an early read on expected tax revenue and lets companies start paying via instalments sooner rather than in one lump sum later.
ECI waiver — who's exempt
Companies don't need to file ECI if their annual revenue doesn't exceed the IRAS-set threshold and their ECI for the year is nil. This waiver is a genuine time-saver for small and dormant companies, but it only applies when both conditions are met — high-revenue companies with zero taxable income still generally need to file.
Worked example
| Financial Year End | ECI Due | Corporate Tax Return Due |
|---|---|---|
| 31 December 2026 | 31 March 2027 | 30 November 2027 |
| 30 June 2026 | 30 September 2026 | 30 November 2027 |
Note that the Corporate Tax Return deadline is fixed at 30 November of the following year regardless of your financial year end — it's only the ECI deadline that shifts based on your specific year-end date.
GST Filing — Usually Quarterly
Most GST-registered businesses file quarterly, with the return and any payment due one month after the accounting period closes. Some businesses may be assigned a different cycle by IRAS depending on their registration circumstances.
What Happens If You File Late
| Situation | Consequence |
|---|---|
| Late individual filing | IRAS may issue an estimated Notice of Assessment based on available information, plus a late filing penalty |
| Late payment of assessed tax | A 5% late payment penalty applies, with an additional penalty for every month it remains unpaid (up to a cap) |
| Repeated or serious non-compliance | IRAS can compound the offence with a fine, or in serious or persistent cases, prosecute in court |
| Late Corporate Tax filing | Similar escalating penalties apply to companies, alongside potential estimated assessments |
In practice, IRAS is generally reasonable with taxpayers who proactively reach out before a deadline if they anticipate difficulty filing on time — waiting until after the deadline to explain a problem is a much weaker position than flagging it in advance.
Frequently Asked Questions
Exact dates can shift slightly year to year and if they fall on weekends/holidays. Always confirm current dates on the official IRAS website.