Singapore’s corporate tax cycle has two main filings: Estimated Chargeable Income, or ECI, and the annual Corporate Income Tax Return through Form C-S, Form C-S (Lite) or Form C.
ECI is due within 3 months after the company’s financial year end unless an ECI filing waiver applies. The annual tax return is due by 30 November for the relevant Year of Assessment.
Singapore’s Corporate Income Tax rate is 17% of chargeable income. After reviewing the filing, IRAS issues a Notice of Assessment. Any tax due must be paid within 1 month from the notice date.
Corporate tax filing is separate from filing an Annual Return with ACRA. It is also separate from GST, payroll reporting and the company’s accounting obligations.
This guide gives company owners an overview of the full IRAS Corporate Income Tax cycle. It links to our focused guides where a filing stage needs a deeper explanation.
What is the Singapore Corporate Income Tax cycle?
The tax cycle starts with the company’s accounting records and ends after IRAS issues the final assessment and any tax balance is paid.
| Stage | What the company does | Usual timing |
|---|---|---|
| 1. Maintain records | Keep complete accounting records, invoices, bank statements and supporting documents. | Throughout the financial year |
| 2. Close the accounts | Prepare the financial statements and identify the company’s accounting profit or loss. | After the financial year end |
| 3. File ECI | Report an estimate of taxable income, unless the company qualifies for an ECI filing waiver. | Within 3 months after FYE |
| 4. Prepare the tax computation | Adjust the accounting result for tax purposes and calculate chargeable income. | Before the annual tax return |
| 5. File the annual tax return | Submit Form C-S, Form C-S (Lite), Form C or the applicable dormant-company return. | By 30 November |
| 6. Review the assessment | Check the Notice of Assessment against the company’s filing and earlier ECI assessment. | After IRAS processes the return |
| 7. Pay or receive a refund | Pay any balance due, or receive a refund where excess tax was paid. | Within 1 month from the NOA date |
IRAS summarises these duties in its basic Corporate Income Tax guide.
How do FYE, basis period and Year of Assessment fit together?
The company’s financial year end, or FYE, closes its accounting period. The income earned during that period is then assessed in a Year of Assessment, or YA.
Singapore assesses Corporate Income Tax on a preceding-year basis. For a company with a 31 December 2025 FYE, the accounting period ending in 2025 is the basis period for YA 2026.
A non-December FYE follows the same rule. An accounting period ending in 2025 is assessed in YA 2026.
Our guide to the Year of Assessment and basis period explains this relationship in more detail.
A newly incorporated company whose first set of accounts covers more than 12 months may need to attribute its income or loss across 2 YAs. Check this before filing the first annual tax return.
What is the Corporate Income Tax rate in Singapore?
Singapore’s headline Corporate Income Tax rate is 17%.
The rate is applied to chargeable income, not to revenue and not automatically to the accounting profit shown in the financial statements.
The final tax can be lower after applying:
- Tax-deductible business expenses
- Capital allowances
- Unutilised losses or capital allowances brought forward, where the conditions are met
- The start-up tax exemption or partial tax exemption
- YA-specific rebates or other reliefs
What income is taxable may also depend on the source of the income, the company’s tax residency and any applicable exemption. Our introduction to how Singapore Corporate Income Tax works covers the broader framework.
For the current rate and exemption rules, refer to IRAS’s Corporate Income Tax rate and exemption guidance.
How is chargeable income calculated?
The company’s accounting profit is only the starting point.
A tax computation adjusts the accounting result to arrive at the income chargeable to tax. Common adjustments include:
- Adding back expenses that are not deductible for tax purposes
- Removing receipts that are not taxable
- Separating non-trade income where required
- Claiming capital allowances on qualifying fixed assets
- Applying eligible losses, donations, reliefs or further deductions
A business expense is deductible when it is incurred wholly and exclusively in producing income, is revenue rather than capital in nature, and is not prohibited by the Income Tax Act.
Ordinary operating costs such as salaries, rent, accounting fees and advertising can be deductible when they meet these conditions. Private expenses, capital costs and expenses unrelated to earning income are not deductible.
The company should prepare a tax computation every year, including where it files Form C-S or Form C-S (Lite) and does not submit the computation with the return. IRAS may request it later.
IRAS explains the required adjustments in its tax computation guide.
What Corporate Income Tax exemptions may apply?
Two common exemption schemes reduce the amount of normal chargeable income subject to the 17% rate.
| Scheme | Current exemption | Who may use it? |
|---|---|---|
| Tax exemption for qualifying new start-up companies | 75% exemption on the first S$100,000 and 50% on the next S$100,000 of normal chargeable income | Qualifying companies for their first 3 consecutive YAs |
| Partial tax exemption | 75% exemption on the first S$10,000 and 50% on the next S$190,000 of normal chargeable income | Companies that are not claiming the start-up tax exemption |
A new company does not qualify for the start-up exemption merely because it was recently incorporated. It must meet the ownership and Singapore tax-residency conditions. Investment holding companies and companies undertaking property development do not qualify for the start-up scheme, although they may qualify for the partial tax exemption.
The start-up exemption is limited to the company’s first 3 consecutive YAs. A loss-making or inactive YA still counts as one of those 3 YAs even if there is no exemption to claim for that year.
Temporary rebates may also apply for a particular YA. These measures change from year to year and should not be treated as permanent. See our YA 2026 Corporate Income Tax rebate guide for the current measure.
What is ECI and when must it be filed?
Estimated Chargeable Income is the company’s estimate of its taxable income for a YA.
A company must file ECI within 3 months after FYE unless it qualifies for a filing waiver or IRAS has specifically exempted it. The usual waiver applies when:
- Its annual revenue is S$5 million or less; and
- Its ECI is nil.
Both conditions must be met.
After processing a positive ECI, IRAS issues a Notice of Assessment for the estimated tax. Eligible Singapore-registered companies receive more GIRO instalments when they file earlier.
ECI is not the final Corporate Income Tax Return. Our dedicated ECI filing guide explains the waiver, deadline, calculation and GIRO instalment structure.
Which annual Corporate Income Tax Return should the company file?
The company later reports its actual taxable income through Form C-S, Form C-S (Lite), Form C or the applicable dormant-company return.
| Return | Main eligibility | Documents submitted with the return |
|---|---|---|
| Form C-S (Lite) | Qualifies for Form C-S and has annual revenue of S$200,000 or less | Keep the financial statements and tax computation; submit them only if IRAS requests them |
| Form C-S | Singapore-incorporated, annual revenue of S$5 million or less, income taxed only at 17%, and no specified complex claims | Keep the financial statements and tax computation; submit them only if IRAS requests them |
| Form C | Does not qualify for Form C-S or Form C-S (Lite) | Financial statements, tax computation and supporting schedules are submitted |
| Form for Dormant Company | Did not carry on business and had no income for the whole basis period | Simplified declarations through myTax Portal |
Form C-S and Form C-S (Lite) are simplified returns. They do not remove the company’s duty to prepare proper accounts and a tax computation.
Our guide to Form C, Form C-S and Form C-S (Lite) covers the eligibility tests and filing differences in more detail.
When is the annual Corporate Income Tax Return due?
Form C-S, Form C-S (Lite) and Form C are due by 30 November each year.
This deadline applies even if the company:
- Made a loss
- Had no tax payable after exemptions
- Already filed ECI
- Filed its Annual Return with ACRA
- Did not receive a filing reminder from IRAS
A company with an approved filing waiver does not need to file for the period covered by the waiver.
For YA 2023 to YA 2027, IRAS currently gives an automatic 15-day extension to Form C-S returns filed through approved Seamless Filing From Software. This is a specific software-filing concession, not a general 15 December e-filing deadline.
Check the current filing season requirements on IRAS’s Corporate Income Tax Filing Season 2026 page.
What should the company prepare before filing?
The exact documents depend on the company’s activities and return type, but a typical filing file includes:
- Finalised financial statements
- Detailed profit and loss breakdown
- Tax computation
- Capital allowance schedules
- Schedules for losses, donations and other claims
- Invoices, contracts and supporting documents for material deductions
- Details of foreign income, related-party transactions or tax credits where relevant
- Prior-year assessments and revised computations where relevant
The records should support the figures filed, not merely provide totals. IRAS requires companies to retain relevant source documents, accounting records, schedules and bank statements for at least 5 years from the relevant YA.
Keeping the records complete throughout the year is easier than reconstructing them shortly before the filing deadline.
How is the Corporate Income Tax Return filed?
The return is filed through myTax Portal.
The person submitting it must have the Corppass “Approver” role for the Corporate Tax (Filing and Applications) digital service. A properly authorised tax agent can also file for the company.
Before submission:
- Confirm the correct YA and basis period.
- Confirm whether ECI was filed and whether any ECI assessment was paid.
- Complete the financial statements and tax computation.
- Select the correct return type.
- Review the pre-filled information and brought-forward tax items.
- Check that claims are supported by the required schedules and documents.
- Save the filing acknowledgement after submission.
Our Corppass guide provides more background on business access to government digital services.
What happens after the company files?
IRAS reviews the return and issues a Notice of Assessment, or NOA.
The NOA states the assessed chargeable income and tax payable. Compare it with:
- The return that was filed
- The ECI assessment
- Tax already paid
- Any exemptions, rebates or credits claimed
If the final tax is higher than the amount assessed or paid through ECI, the company pays the balance. If it is lower, IRAS refunds the excess tax paid.
Corporate Income Tax must be paid within 1 month from the NOA date. Filing an objection does not suspend the payment deadline.
Our guide on how to pay Corporate Income Tax explains the NOA, GIRO, payment channels, payment-status checks and late-payment consequences.
Do loss-making, dormant and new companies still need to file?
Loss-making companies
A company that carried on business or received income must file its annual Corporate Income Tax Return even if it made a loss or has no tax payable.
Tax losses can be carried forward or used for other relief when the relevant conditions are met. They must still be calculated and reported correctly.
Dormant companies
A dormant company for IRAS purposes is one that did not carry on business and had no income for the whole basis period.
It files the simplified Form for Dormant Company unless IRAS has granted a waiver from filing. A company that has received a waiver must notify IRAS if it restarts business or begins receiving income.
See our Corporate Income Tax guide for dormant companies for the waiver and recommencement rules.
New companies
A new company’s first filing depends on when it closes its first accounts and when it starts business or receives income.
If the first accounting period is longer than 12 months, the company may need to report income across 2 YAs. Do not assume that the first return covers only one YA.
Do not rely only on whether IRAS sent a reminder. The company and its directors remain responsible for checking whether a return is due.
Does filing with ACRA cover the IRAS tax return?
No. The Annual Return filed with ACRA and the Corporate Income Tax Return filed with IRAS are separate obligations.
Preparing financial statements for ACRA or filing XBRL may support the tax filing, but it does not replace ECI or Form C-S, Form C-S (Lite) or Form C.
For the wider company compliance year, see our Singapore company annual compliance guide.
What happens if the company files late?
Late filing or non-filing is an offence.
IRAS may:
- Issue an estimated Notice of Assessment
- Require the estimated tax to be paid within 1 month
- Offer to compound the offence
- Issue notices to the director
- Issue a summons or take court action
An estimated assessment does not remove the filing obligation. The company should file the outstanding return and address the assessment promptly.
If returns remain outstanding for multiple years, the company and its directors can face heavier penalties and court action.
IRAS sets out the current consequences in its late-filing guidance.
Corporate Income Tax filing checklist
- Confirm the company’s FYE.
- Identify the correct YA and basis period.
- Keep the accounting records complete and reconciled.
- Check whether ECI must be filed within 3 months after FYE.
- Prepare the financial statements.
- Prepare the tax computation and supporting schedules.
- Check whether the start-up or partial tax exemption applies.
- Select Form C-S (Lite), Form C-S, Form C or the dormant-company return.
- Confirm Corppass Approver access.
- File the annual return by 30 November unless a specific concession applies.
- Save the filing acknowledgement.
- Review the NOA against the return and ECI.
- Pay any balance within 1 month from the NOA date.
- Retain the tax and accounting records for at least 5 years from the relevant YA.
Frequently asked questions
What is Singapore’s Corporate Income Tax rate?
The headline rate is 17% of chargeable income. Tax exemptions, rebates, deductions, capital allowances and reliefs may reduce the final amount payable.
Does every company need to file ECI?
Most companies do. The usual ECI filing waiver applies where annual revenue is S$5 million or less and ECI is nil. Both conditions must be met.
When is ECI due?
ECI is due within 3 months after the company’s financial year end.
When is Form C-S, Form C-S (Lite) or Form C due?
The general filing deadline is 30 November each year. IRAS currently gives a limited 15-day extension for qualifying Form C-S returns filed through Seamless Filing From Software for YA 2023 to YA 2027.
Is ECI the same as the annual tax return?
No. ECI is an estimate filed earlier in the tax cycle. Form C-S, Form C-S (Lite) or Form C reports the company’s actual taxable income later.
Must a loss-making company file a tax return?
Yes. A company that carried on business or received income must file even if it made a loss or has no tax payable.
Must a dormant company file?
A dormant company files the simplified Form for Dormant Company unless IRAS has granted it a waiver from filing.
When must Corporate Income Tax be paid?
Tax must be paid within 1 month from the date of the Notice of Assessment unless the company has an approved instalment arrangement.
How long must the company keep its tax records?
The company must retain its source documents, accounting records, schedules and related business records for at least 5 years from the relevant Year of Assessment.
Does filing an Annual Return with ACRA replace the IRAS tax return?
No. The ACRA Annual Return and IRAS Corporate Income Tax Return are separate filings.
Need help with the Corporate Income Tax cycle?
Leftright Corporate can help prepare the tax computation, file ECI and the annual Corporate Income Tax Return, and review the resulting assessment.
See our corporate tax computation and filing service for more information.
