The Inland Revenue Authority of Singapore (IRAS) has published its guidance for the Year of Assessment (YA) 2026 Corporate Income Tax filing season. Companies required to file their YA 2026 Corporate Income Tax Return should submit the return electronically through myTax Portal by 30 November 2026.
The guidance also highlights filing eligibility requirements, preparatory steps for electronic filing and additional digital support, including the myTax Portal Troubleshooting Assistant (Corporate Tax) for resolving common access and login issues.
Key impacts for companies
30 November 2026 remains the key filing deadline
Companies generally need to lodge their YA 2026 Corporate Income Tax Return by 30 November 2026, unless IRAS has granted the company a waiver from filing.
The requirement can apply even where the company has incurred a tax loss. Companies that were dormant during the relevant financial year should also confirm their status with IRAS rather than assuming that no tax filing is required. From a compliance perspective, companies should therefore establish the filing requirement early, particularly for:
- loss-making companies;
- dormant or previously dormant companies;
- newly incorporated companies;
- companies that have recommenced operations; and
- companies with an earlier assessment still under review by IRAS.
Directors remain responsible for the company’s tax filing
The appointment of an external tax agent does not transfer the company’s ultimate filing responsibility. IRAS specifically highlights directors’ responsibility for ensuring that the company’s return is both accurate and submitted on time. Late filing or failure to file may result in penalties of up to S$5,000.
Companies should therefore maintain appropriate internal review and approval procedures rather than treating the tax filing process solely as an external adviser function.
Companies should reassess which return they qualify to use
The appropriate return depends on the company’s circumstances.
A Singapore-incorporated company may generally use Form C-S where its annual revenue does not exceed S$5 million, its income is taxable at the prevailing 17% corporate income tax rate and it does not make specified claims such as group relief, current-year loss or capital allowance carry-back, investment allowance or foreign tax credit claims.
A company that satisfies the Form C-S conditions and has annual revenue of S$200,000 or less may qualify for Form C-S (Lite).
Companies that do not qualify for these simplified filing options generally file Form C, together with the required financial statements, tax computation and supporting schedules.
This assessment should be completed before preparation begins, as transactions or tax relief claims during the year may affect the form available to the company.
Digital access should be checked before the filing period becomes busy
Personnel or tax agents filing through myTax Portal must have the appropriate Corppass authorisation for the Corporate Tax filing service.
IRAS has also introduced the myTax Portal Troubleshooting Assistant (Corporate Tax), which provides guided assistance for common login and digital-service access problems.
This is primarily an administrative enhancement rather than a change to the underlying tax rules, but it should help businesses resolve access problems before they disrupt filing.
Greater opportunity to automate Form C-S preparation and filing
Eligible Form C-S filers may use IRAS’ Seamless Filing From Software functionality to prepare and transmit information from supported accounting software to IRAS.
For companies with suitable systems and sufficiently structured accounting data, this may reduce manual data entry and improve consistency between accounting records and information reported in the tax return.
Automation does not, however, remove the need to review the underlying tax treatment, adjustments and eligibility for deductions or reliefs.
Practical issues
Companies and advisers should pay particular attention to the following areas during the YA 2026 filing cycle:
- Confirm filing status early. Dormant status, losses or a lack of taxable income do not automatically mean that no return is required.
- Check Corppass permissions. Filing access should be tested well before 30 November to avoid last-minute authorisation or portal-access difficulties.
- Reconfirm Form C-S eligibility each year. A company that qualified previously may cease to qualify because of revenue growth or particular tax claims.
- Complete tax adjustments carefully. Accounting profit should be reconciled to taxable income, including consideration of non-deductible expenses, capital allowances, exempt income and other relevant tax adjustments.
- Maintain adequate supporting records. The use of simplified filing forms does not reduce the company’s obligation to maintain records supporting figures reported to IRAS.
- Review functional currency information. Companies using a non-Singapore-dollar functional currency should ensure the relevant corporate profile information with IRAS is current.
- Avoid common classification errors. IRAS has highlighted errors such as claiming non-deductible expenditure, omitting income because of weak record keeping and incorrectly completing adjusted profit or loss information in Form C-S (Lite).
- Build in sufficient review time. Tax computations and supporting documentation should be finalised sufficiently early to allow management and directors to review material tax positions before submission.
Action plan
Companies should begin preparing for YA 2026 filing ahead of the 30 November 2026 deadline by confirming their filing obligations, identifying the correct return, verifying Corppass access and reviewing the completeness of financial and tax records.
Finance teams should also coordinate with their tax advisers early where there are significant tax adjustments, complex transactions, foreign income, loss utilisation, group relief or other claims that may affect Form C-S eligibility.
Where accounting software is capable of supporting IRAS’ seamless filing functionality, businesses may also consider whether greater integration between their accounting and tax-filing processes could improve efficiency while maintaining appropriate review controls.
Source: IRAS, 3 August 2026.