Form C, C-S and C-S Lite filing — Documents required and templates

Form C, C-S and C-S Lite are the three annual corporate income tax returns a Singapore company files with IRAS, and each requires a different set of supporting documents: full financial statements and tax computation schedules for Form C, a shorter set for Form C-S, and minimal supporting records for Form C-S Lite. This article lists exactly what to prepare for each.

Raffles Corporate Services works with a panel of corporate and employment law firms; this article is general information, not legal advice.

What Form C, C-S and C-S Lite filing covers

Every Singapore company must file an annual corporate income tax return, even if it made a loss or is dormant. Section 62 of the Income Tax Act 1947 requires a person chargeable to tax to furnish a return of income for each Year of Assessment when required to do so by the Comptroller of Income Tax, and this return takes the form of Form C, Form C-S or Form C-S (Lite) depending on the company’s eligibility. Form C is the full return with the most extensive supporting schedules; Form C-S is a simplified return for qualifying smaller companies; Form C-S (Lite) is a further-simplified version for the smallest, most straightforward companies.

Who this is for

This guide is for directors, finance managers and company secretaries responsible for a Singapore company’s annual corporate tax filing, whether the return is prepared in-house or by an outsourced tax agent. It covers what to gather before filing, not the mechanics of the myTax Portal e-filing screens themselves.

Eligibility and the documents each form requires

Form C-S (Lite) is available to companies with annual revenue of S$200,000 or below that also qualify for Form C-S and have straightforward tax affairs; it requires only a handful of fields to be completed online, but the company must still have prepared and be ready to produce, on request, its financial statements and full tax computation. Form C-S is available to companies with annual revenue of S$5 million or below that meet the other qualifying conditions (Singapore-incorporated, no claims for group relief as a claimant company beyond permitted items, and not claiming certain reliefs restricted to Form C filers); it requires a tax computation and supporting schedules to be kept on hand, with only summary figures entered on the form itself, though IRAS may call for the full computation. Form C is required for all other companies, and must be filed together with:

• Audited or unaudited financial statements (depending on whether the company qualifies for audit exemption under the Companies Act 1967);
• A detailed tax computation reconciling accounting profit to chargeable income;
• Supporting schedules for capital allowances, revenue and non-revenue items, and any tax adjustments claimed;
• Relevant supporting documents for any incentives, reliefs or exemptions claimed, such as the Start-Up Tax Exemption or Partial Tax Exemption computations.

Across all three forms, the underlying documents a company should have assembled before filing are the same core set: the trial balance and financial statements for the Year of Assessment, the tax computation and its supporting schedules, the fixed-asset and capital allowance schedule, records of any related-party transactions, and confirmation of the company’s revenue for the year (to test which form it qualifies to file).

What the supporting templates actually contain

The tax computation template starts from the accounting profit or loss per the financial statements and works through a series of standard adjustments: adding back non-deductible expenses (such as private motor vehicle expenses, certain donations, and general provisions), deducting non-taxable income (such as certain dividend and gains items), adding back or deducting temporary differences, and then applying capital allowances, trade losses brought forward, and any exemptions such as the Start-Up Tax Exemption or Partial Tax Exemption, to arrive at chargeable income. A capital allowance schedule template lists each qualifying fixed asset, its cost, the allowance claimed in the current year (whether under the one-year write-off, three-year write-off, or the asset’s prescribed working life), accumulated allowances claimed, and the residual tax written-down value — this should reconcile to the fixed-asset register used for accounting depreciation, even though the tax and accounting depreciation figures themselves will usually differ.

A group relief or exemption-claim schedule, where relevant, should show the computation supporting the specific relief claimed, with cross-references back to the financial statements line items it relies on, so that if IRAS raises a query the preparer is not reconstructing the workings from scratch months later.

Cost and timeline

Numerically, Form C-S (Lite) preparation typically costs from around S$300 to S$600 when outsourced to a tax agent for a simple company; Form C-S preparation typically runs from S$600 to S$1,500; and full Form C preparation, given its more extensive schedules, typically starts from around S$1,500 and rises significantly for companies with multiple tax adjustments, group relief claims or incentive claims. The filing deadline for all three forms is 30 November following the relevant Year of Assessment, and this is a hard deadline — extensions are not routinely granted. Financial statements and the tax computation should ideally be finalised at least 4 to 6 weeks before this deadline to allow time for review and, where used, tax agent sign-off before e-filing on the myTax Portal.

Companies should also keep in mind the separate, earlier Estimated Chargeable Income (ECI) filing, due within 3 months of financial year end, which is a distinct filing from Form C/C-S/C-S Lite but draws on the same underlying financial records.

Worked example — which form applies

A Singapore-incorporated trading company with annual revenue of S$180,000 for the Year of Assessment, no group relief claims and straightforward tax affairs, qualifies to file Form C-S (Lite) — it need only complete a small number of fields online, though it should still hold its financial statements and tax computation on file. If the same company’s revenue rose to S$3 million the following year, it would no longer qualify for C-S (Lite) but would still qualify for Form C-S, provided it continues to meet the other qualifying conditions, and would need to prepare (though not submit) a full tax computation. If revenue rose further to S$7 million, exceeding the S$5 million Form C-S threshold, the company would need to file the full Form C, together with its financial statements, tax computation and all supporting schedules submitted to IRAS rather than merely held on file.

Record retention after filing

Filing the return does not end the documentation obligation. Section 67 of the Income Tax Act 1947 requires every person carrying on a business to keep records sufficient to enable income and allowable deductions to be readily ascertained, and IRAS expects these records — including the financial statements, tax computation and all supporting schedules used to prepare Form C, C-S or C-S Lite — to be retained for at least 5 years from the relevant Year of Assessment. This applies whether or not the underlying documents were actually submitted with the return: Form C-S and C-S Lite filers in particular should not treat the reduced amount keyed into the online form as reducing what must be kept on file, since IRAS retains the right to call for the full computation and financial statements within the retention period.

Where a tax agent has prepared the filing, the company should still hold its own copy of the final tax computation and supporting schedules rather than relying solely on the agent’s records, particularly if the agent relationship changes before the retention period expires.

Step-by-step process to prepare and file

1. Confirm the company’s revenue for the Year of Assessment to determine which form it is eligible to file (Form C-S Lite, Form C-S, or Form C).
2. Finalise the financial statements for the relevant financial year, reconciled to the trial balance.
3. Prepare the tax computation, reconciling accounting profit to chargeable income, adjusting for non-deductible expenses, capital allowances and any exemptions or reliefs.
4. Assemble supporting schedules — capital allowances, related-party transactions, and any incentive or exemption claims.
5. Authorise the preparer (company staff or tax agent) on the myTax Portal to file on the company’s behalf, if not already authorised.
6. E-file the appropriate form by 30 November, retaining the full financial statements and tax computation even where the form itself only requires summary figures.
7. Retain all supporting documents for at least 5 years in case IRAS requests them after filing.

Common mistakes and gotchas

• Filing Form C-S (Lite) without keeping the full tax computation on hand. The simplified form reduces what is keyed in, not what must be prepared and retained — IRAS can still request the full computation and financial statements.
• Assuming eligibility carries over from the prior year. Revenue can cross the S$200,000 or S$5 million thresholds between years, changing which form the company must file.
• Missing capital allowance schedules. Capital allowances are one of the most common areas of error in a tax computation, particularly where a fixed-asset register has not been properly maintained during the year.
• Confusing the ECI filing with the Form C/C-S/C-S Lite filing. These are two separate obligations on two separate timelines, and filing one does not satisfy the other.
• Leaving financial statements unfinished close to 30 November. Because the deadline is generally not extended, a late-finished set of accounts routinely causes a late corporate tax filing and exposes the company to late filing penalties.
• Not retaining supporting documents after filing. IRAS can request the underlying records well after the filing date, and the obligation to keep them does not end once the return is submitted.
• Reusing last year’s capital allowance schedule without updating for the year’s additions and disposals. This is a frequent source of over- or under-claimed allowances.
• Not cross-referencing exemption claims to the financial statements. A Start-Up Tax Exemption or Partial Tax Exemption claim that cannot be traced back to specific income and adjustment lines invites a query.

Related guides

For the broader corporate tax landscape that Form C/C-S/C-S Lite sits within, see our cross-site guide on Singapore Budget 2026 corporate impact briefings. Companies that also employ foreign staff should see our cross-site note on the Singapore Work Permit 2026 employer guide, since payroll costs and levies feature directly in the tax computation. For the eligibility criteria behind each of the three forms in more depth, see our companion article Form C, C-S and C-S Lite filing — Eligibility and requirements checklist.

The Inland Revenue Authority of Singapore (iras.gov.sg) is the primary source for current filing procedures and deadlines, and the Accounting and Corporate Regulatory Authority (acra.gov.sg) governs the financial statements and audit-exemption rules that feed into the tax computation.

FAQs

Which form does my company need to file?
It depends on annual revenue and the complexity of the company’s tax affairs: Form C-S (Lite) for revenue of S$200,000 or below with straightforward affairs, Form C-S for revenue of S$5 million or below meeting the other qualifying conditions, and Form C for all other companies.

Do I need to submit financial statements with Form C-S or C-S Lite?
Not with the online form itself, but the company must still have prepared its financial statements and full tax computation and be ready to produce them if IRAS requests them.

What is the filing deadline?
30 November following the relevant Year of Assessment for all three forms, and this deadline is not routinely extended.

What happens if I file late?
IRAS can impose late filing penalties, issue an estimated Notice of Assessment based on its own judgement of the company’s income, and in serious cases pursue further enforcement action, so it is treated as a firm statutory deadline.

Does a dormant company still need to file?
Generally yes, unless the company has applied for and been granted a waiver of the requirement to file, in which case a separate, simpler declaration process applies.

Can I switch from Form C to Form C-S once my revenue falls below S$5 million?
Yes, provided the company meets the other qualifying conditions for Form C-S for that Year of Assessment; eligibility is tested afresh each year rather than being a permanent designation.

Need help with this? Call, SMS or WhatsApp +65 8501 7133, or email [email protected]. Raffles Corporate Services works with a panel of corporate and employment law firms; this article is general information, not legal advice.