When is the corporate tax return due?

By 30 November of the Year of Assessment, which is the calendar year following your financial year end. All three forms share this deadline.

Does the wrong form delay my assessment?

Yes. Filing a simplified form when you do not qualify can trigger queries and reprocessing, pushing back your Notice of Assessment.

Form C-S vs Form C-S (Lite) vs Form C explained

Q: What disqualifies a company from Form C-S?

Claiming carry-back of capital allowances or losses, group relief, investment allowance, or foreign tax credit generally means you must file Form C instead.

Form C-S vs Form C-S (Lite) vs Form C

Revenue thresholds, what each form asks for, and why filing the wrong one delays your assessment.

Alyst editorial team

Updated 7 Jun 2026 · 10 min read

In 30 seconds

Form C-S is a simplified return for companies with annual revenue of five million dollars or less that meet the qualifying conditions. Form C-S (Lite) is an even shorter version for companies with revenue of two hundred thousand dollars or less. Form C is the full return for everyone else. All three are filed by 30 November of the Year of Assessment through myTax Portal.

Singapore has three corporate income tax returns. Which one you file depends mostly on your revenue and on what reliefs you are claiming.

The three forms

Form C-S — a simplified return for companies with annual revenue of S$5 million or less that meet the qualifying conditions.
Form C-S (Lite) — an even shorter version for companies with annual revenue of S$200,000 or less.
Form C — the full return, for every company that does not qualify for the simplified forms.

What each asks for

Form C-S (Lite) captures only a handful of essential fields. Form C-S adds a tax computation and standard declarations. Form C requires the full computation plus supporting schedules and financial statements.

Qualifying conditions

Beyond revenue, Form C-S requires that the company is incorporated in Singapore, derives only income taxable at the prevailing corporate rate, and is not claiming reliefs such as carry-back of losses, group relief, investment allowance, or foreign tax credit. Claiming any of those pushes you to Form C.

The deadline is the same

Whichever form applies, the filing deadline is 30 November of the Year of Assessment — the calendar year following your financial year end — through myTax Portal. Filing the wrong form can trigger queries and delay your Notice of Assessment. Check whether you even need to file ECI first, and see your dates in the deadline tracker.

Frequently asked questions

This guide is general information, not legal or tax advice. Confirm requirements with ACRA and IRAS, or speak to your corporate secretary.