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Form C-S is the simplified Corporate Income Tax return for Singapore-incorporated companies with annual revenue of S$5 million or below. IRAS, the Singapore tax authority, wants it by 30 November every year, even when the company made a loss. Smaller companies below S$200,000 revenue can file the shorter Form C-S (Lite).
Checked against IRAS pages.
This is an independent guide, not IRAS and not a tax agent. If you ask for quotes here, the request goes to accounting firms that may pay us a referral fee.
Which IRAS tax return does your company file?
IRAS has three versions of the corporate return. The choice depends on size, where the company is incorporated and what kind of income it has.
| Form C-S (Lite) | Form C-S | Form C | |
|---|---|---|---|
| Who | Singapore-incorporated, revenue S$200,000 or below | Singapore-incorporated, revenue S$5 million or below | All companies |
| Fields | 6 | 18 | Full return |
| Accounts and tax computation sent | No, keep on file | No, keep on file | Yes |
| Typical time to fill in | Short | At least 10 minutes | At least 30 minutes |
Both short forms have two extra conditions. The company must only have income taxed at the 17% rate, and it must not claim any of these in the Year of Assessment:
- Carry-back of current year capital allowances or losses
- Group relief
- Investment allowance
- Foreign tax credit and tax deducted at source
There are two exceptions to the 17% rule. One-tier tax exempt Singapore dividends and specified foreign-sourced income exempt under section 13(8) of the Income Tax Act do not disqualify you. Anything else taxed at a concessionary rate, such as under a tax incentive, means Form C.
Revenue here is the main income source and does not count separate-source income such as interest. A Lite-eligible company may still file Form C-S or Form C if it prefers.
When is Form C-S due?
The date is 30 November, every year, for Form C-S, Form C-S (Lite) and Form C. It is a fixed date and does not move with your financial year end. A company that closed its accounts on 31 December has 11 months. One that closed on 31 March has more than 7 months.
A new company's first set of accounts can run for more than 12 months from incorporation. Then the profit must be split across two Years of Assessment, because one basis period cannot be longer than 12 months. You fill in two sets of line items. IRAS lets you time-apportion if you cannot tie profit to each period directly.
The return comes after the earlier ECI filing. See the ECI page for that step. Tax return dates are separate from ACRA's annual return, which the annual return page covers.
How do you file Form C-S?
You file through IRAS myTax Portal. Before you start:
- Confirm the company meets the Form C-S conditions.
- Have a person authorised as Approver for Corporate Tax (Filing and Applications) in Corppass. See the Corppass page.
- Have the Singpass and the UEN ready.
- Have the financial statements and tax computation ready, even though you do not send them.
Then log in to mytax.iras.gov.sg and open the File Form C-S/ Form C-S (Lite) service. If revenue is S$200,000 or below, the form type selection offers the Lite version. You can save a draft, and IRAS keeps it until the due date. The session logs you out after 15 minutes of no activity, with a 2 minute warning. After submitting you get an instant acknowledgement, which stays under View Corporate Tax Notices/ Letters. Do not send that page to IRAS.
IRAS pre-fills unused capital allowances, losses and donations brought forward from the last assessment. Check them against your own records and correct them in the Company's Declaration if they differ.
What should you prepare before filing?
Even when you do not attach documents, IRAS can ask for them. Keep:
- Audited or unaudited financial statements. Small companies and dormant companies do not need an audit under the Companies Act. The audit exemption page has the tests.
- The tax computation and supporting schedules.
- A declaration for claiming writing-down allowances on intellectual property rights, if you claim them. This one is filed with the return.
For Form C you also need Form IRIN 301, a detailed profit and loss statement and any claim forms, all as PDF files. If your accounts go to ACRA in XBRL format, the XBRL page explains that separate filing.
What if your company did not trade?
A company still files even with no income. If it did not carry on business and had no income for the whole period, it counts as dormant for IRAS. It can file the Form for Dormant Company, which has two fields and takes about 5 minutes. The dormant company page has the waiver conditions.
What happens if you file late or pay late?
Late or non-filing is an offence. IRAS can take these steps, in no fixed order:
- Issue an estimated Notice of Assessment. You pay within 1 month, and you can object within 2 months by sending the return, accounts and tax computation.
- Offer a composition amount of up to S$5,000 per offence, set by your past record. GIRO is not accepted for it.
- Send a section 65B(3) notice to a director.
- Issue a Notice to Attend Court or a summons to the company and the people running it, directors included.
You can appeal a composition amount online, but IRAS only considers it if you filed the overdue return before the composition due date and filed on time for the past 2 years.
Tax itself is due 1 month after the Notice of Assessment. A 5% penalty applies to unpaid tax. After 60 days, another 1% a month can be added, to a maximum of 12% of the unpaid tax. For S$10,000 of tax, IRAS shows a S$500 penalty at the first stage.
IRAS announced a Corporate Income Tax Rebate of 50% of tax payable, up to S$40,000, for the current Year of Assessment. It is worked out automatically from the return you file, so you do not claim it separately.
Should you hire an accountant for Form C-S?
For a company with a simple profit and loss, the form itself is quick. The time goes into the accounts, the tax computation and spotting what is disallowed. An accounting firm is useful when you have capital allowances, losses, foreign income or a revenue figure that hovers around S$200,000 or S$5 million. The corporate tax page explains the rate and exemptions, and the accounting services page shows what firms usually include. Ask for the deadline, the scope and the fee in writing.
If you want someone else to prepare and file it, use the quote form on this page and we pass your request to suitable firms.
Sources
- IRAS, Overview of Form C-S, Form C-S (Lite) and Form C, https://www.iras.gov.sg/taxes/corporate-income-tax/form-c-s-form-c-s-(lite)-form-c-filing/overview-of-form-c-s-form-c-s-(lite)-form-c (eligibility, fields, documents).
- IRAS, Guidance on Filing Form C-S, Form C-S (Lite) and Form C, https://www.iras.gov.sg/taxes/corporate-income-tax/form-c-s-form-c-s-(lite)-form-c-filing/guidance-on-filing-form-c-s-form-c-s-(lite)-form-c (30 November, steps, new companies, documents to keep).
- IRAS, Late filing or non-filing of Corporate Income Tax Returns, https://www.iras.gov.sg/taxes/corporate-income-tax/form-c-s-form-c-s-(lite)-form-c-filing/late-filing-or-non-filing-of-Corporate-Income-Tax-Returns-form-c-s-form-c-s-(Lite)-form-c (composition, summons, appeals).
- IRAS, Late payment or non-payment of Corporate Income Tax, https://www.iras.gov.sg/taxes/corporate-income-tax/corporate-income-tax-payment/late-payment-or-non-payment-of-corporate-income-tax (5% penalty, 1% a month, 12% cap).
- IRAS, Estimated Chargeable Income (ECI) Filing, https://www.iras.gov.sg/taxes/corporate-income-tax/estimated-chargeable-income-(eci)-filing (Corporate Income Tax Rebate).
