Quick answer
For YA 2026, the corporate income tax return filing deadline is 30 November 2026. This is a filing-season reminder, not a new tax policy. The return still depends on the company’s facts: whether it carried on business or received income in financial year 2025, whether it is newly incorporated or dormant, and which return it qualifies to use.
Form C-S (Lite) is generally available only to a company that already qualifies for Form C-S and has annual revenue of S$200,000 or below. Form C-S is for qualifying Singapore-incorporated companies with annual revenue of S$5 million or below. A company that does not meet the simplified-return conditions files Form C.
- Check the company’s filing status in myTax Portal and whether IRAS has granted a filing waiver.
- A loss or nil tax payable does not by itself remove the filing requirement.
- A newly incorporated company should check when it closed its first accounts and whether it started business or derived income in 2025.
- A dormant company should check whether myTax Portal shows “No Business Done” or “Active”; the required action differs.
- Prepare financial statements and a tax computation even when they are not submitted with Form C-S or Form C-S (Lite).
Form C-S Lite, Form C-S or Form C: the practical choice
The simplified forms are useful, but they are not automatic. The company must first identify its revenue and then test the other conditions. A small company with straightforward local income may be able to file Form C-S Lite. A larger SME may still use Form C-S if it meets the S$5 million revenue condition and does not make excluded claims. A company with more complex tax positions should expect Form C.
| Return type | Typical company profile | Key point for directors |
|---|---|---|
| Form C-S Lite | Singapore-incorporated company, annual revenue S$200,000 or below, straightforward tax matters | Only 6 essential fields, but books and tax computation must still be ready. |
| Form C-S | Singapore-incorporated company, annual revenue S$5 million or below, meets the other conditions | Simplified filing, but IRAS may request financial statements and tax computation later. |
| Form C | Company that does not qualify for Form C-S or Form C-S Lite | Financial statements, tax computation and supporting documents are filed together with the return. |
YA 2026 filing season: check the obligation before choosing the form
IRAS states that YA 2026 corporate income tax returns are due by 30 November 2026 unless a filing waiver applies. The date is the current filing-season deadline; it does not change the existing Form C-S or Form C-S (Lite) eligibility conditions.
A company that carried on business or received income in financial year 2025 must still file even if it made a loss or has no tax payable. “No profit” and “no filing” are not the same conclusion.
A company incorporated in 2025 must file for YA 2026 if it closed its first set of financial statements in 2025 and derived income or started business in 2025. It need not file for YA 2026 if it closed its first accounts but neither commenced business nor received income in 2025, or if it did not close its first accounts in 2025. Do not decide from the incorporation date alone.
Dormant means that the company did not carry on business and had no income for the whole basis period. Under IRAS’s YA 2026 guidance, a dormant company shown as “No Business Done” in myTax Portal has a filing waiver and need not file, while one shown as “Active” should file using the Form for Dormant Company.
IRAS eligibility conditions to check before choosing Form C-S
Form C-S and Form C-S Lite are not just “shorter forms”. They are available only where the company satisfies the relevant conditions. Based on IRAS guidance, the company should check all of the following before deciding that Form C-S is appropriate:
- the company is incorporated in Singapore;
- annual revenue is S$5 million or below for Form C-S, or S$200,000 or below for Form C-S Lite;
- the company only derives income taxable at the prevailing corporate income tax rate of 17%;
- the company is not claiming carry-back of current year capital allowances or losses;
- the company is not claiming group relief;
- the company is not claiming investment allowance; and
- the company is not claiming foreign tax credit or tax deducted at source.
Revenue should be read carefully. IRAS notes that revenue refers to the company’s main income source, excluding separate-source income such as interest. This matters for companies with deposits, investment income, shareholder loans or mixed revenue streams.
Practical scenarios for Singapore SMEs
New local service company
If revenue is below S$200,000 and the company has only normal local service income, Form C-S Lite may be suitable. Still prepare management accounts, bank reconciliation, expense schedules and a simple tax computation.
Growing SME with GST or payroll
GST registration or payroll does not automatically force Form C. The company may still use Form C-S if it meets the revenue and other conditions, but the tax computation must properly handle deductible expenses, CPF, GST-exclusive amounts and director remuneration.
Company with foreign tax or overseas withholding
If the company wants to claim foreign tax credit or tax deducted at source, Form C-S is generally not the right simplified route. Review the supporting certificates and expect a fuller Form C filing.
Group company or related-party structure
Group relief, complex related-party positions and tax incentives require more care. Do not treat a small revenue number as a shortcut where the tax position itself is not straightforward.
Records to prepare before tax filing
Even where Form C-S Lite or Form C-S does not require financial statements and tax computation to be submitted together with the return, those documents should exist before filing. Filing first and preparing the tax computation later creates obvious audit risk.
- trial balance and financial statements for the financial year;
- tax computation reconciling accounting profit or loss to chargeable income;
- fixed asset schedule and capital allowance workings;
- director fee, salary, CPF and payroll summaries;
- donations, medical expenses, entertainment, private expenses and non-deductible items schedule;
- GST reconciliation if the company is GST-registered;
- related-party transactions and management fee details, if applicable; and
- prior-year Notice of Assessment and any brought-forward loss or capital allowance schedule.
Common mistakes we see in Form C-S / Form C decisions
The most common mistake is choosing the shortest form because the company is “small”. The correct test is eligibility. Another mistake is treating a loss, nil tax payable, recent incorporation or inactivity as an automatic exemption from filing. For YA 2026, check the company’s myTax Portal filing status, any filing waiver, whether business or income arose in financial year 2025, and whether a dormant company is shown as “No Business Done” or “Active”.
For founders, the safest workflow is to decide the form only after the accounts, revenue, tax adjustments and excluded claims have been reviewed. This is especially important for companies with overseas income, unusual one-off receipts, shareholder-funded expenses, GST registration, management fees or group structures.
Frequently asked questions
What is the revenue threshold for Form C-S Lite?
Form C-S Lite is generally available where the company qualifies for Form C-S and has annual revenue of S$200,000 or below. It is intended for companies with straightforward tax matters.
What is the revenue threshold for Form C-S?
Form C-S is for qualifying Singapore-incorporated companies with annual revenue of S$5 million or below, provided the other IRAS conditions are met.
When must a company file Form C instead?
A company should file Form C if it does not qualify for Form C-S or Form C-S Lite, such as where it exceeds the revenue threshold or claims items that are excluded from the simplified forms.
Do I still need a tax computation for Form C-S Lite or Form C-S?
Yes. The tax computation and financial statements may not be submitted together with Form C-S or Form C-S Lite, but the company should prepare and retain them in case IRAS asks for them.
Does a loss-making company still need to file for YA 2026?
A loss does not by itself remove the filing requirement. If the company carried on business or received income in financial year 2025, it must file for YA 2026 unless a filing waiver applies. The correct return still depends on the Form C-S eligibility conditions and any excluded claims, including a carry-back claim.
What is the YA 2026 corporate income tax filing deadline?
The deadline is 30 November 2026, unless IRAS has granted the company a waiver from filing.
Does a dormant company file the same return?
Not necessarily. A dormant company shown as “No Business Done” in myTax Portal has a filing waiver and need not file, while one shown as “Active” should file using the Form for Dormant Company. “Dormant” means that the company did not carry on business and had no income for the whole basis period.
Can a company choose Form C even if it qualifies for Form C-S Lite?
Yes. A company that qualifies for Form C-S Lite may still choose to file Form C-S or Form C, but this does not remove the need to keep proper supporting records.
Official sources
This guide is based on official IRAS guidance and should be checked against the company’s own facts before filing.
- IRAS: Overview of Form C-S / Form C-S Lite / Form CRevenue thresholds, qualifying conditions and filing differences.
- IRAS: Guidance on filing Form C-S / Form C-S Lite / Form CFiling process and practical guidance.
- IRAS: Corporate income tax record keepingRecords that should be retained to support tax filing positions.
- IRAS: Estimated Chargeable Income filing
- IRAS — Corporate Income Tax Filing Season 2026Accessed 22 September 2026.
Continue with related guidance
- ECI filing in Singapore
- Dormant company tax filing
- Expense claims and tax evidence
- Accounting records for Singapore companies
Corporate tax filing service · Ask ProSec to review your filing position
Need help choosing the correct corporate tax return?
Send us your FYE, revenue, draft accounts, profit or loss estimate, GST status and any foreign tax or group relief items. We can check whether Form C-S Lite, Form C-S or Form C is the safer route.