What is ECI and do I need to file them?

ECI stands for estimated chargeable income. ECI is an estimate of the company’s taxable income (after deducting tax-allowable expenses) for a Year of Assessment (YA).

If your company fits both the following criteria, it does not required to file an ECI for that YA:
For the financial year, annual revenue does not exceed $5 million, AND ECI is NIL for the YA.