Edition, eligibility and deadline
Updated 15 May 2026. Form C-S requires Singapore incorporation, revenue at most S$5 million, only income taxable at 17%, and no claim for capital-allowance/loss carry-back, group relief, investment allowance, foreign tax credit or tax deducted at source. From YA 2020, qualifying revenue at most S$200,000 permits C-S (Lite), while C-S or C remains optional. Other companies use C. Annual deadline is 30 November. This FAQ points to the separate documents-to-prepare guidance rather than reproducing its checklist.
Temporary revenue fluctuations and the Lite selection
A company that filed C-S for YA 2025 may still use it for YA 2026 when revenue exceeds S$5 million if every other condition is satisfied: the concession accommodates a temporary fluctuation. If YA 2027 also exceeds S$5 million, use C. Lite appears after entering revenue at most S$200,000 under C-S on Form Type Selection. Foreign-incorporated companies and Singapore branches of foreign companies cannot use C-S, so its E-FILE button is disabled.
Corppass roles
Authorise company staff or a third party for Corporate Tax (Filing and Applications). Approver can complete, approve and submit to IRAS; Preparer completes and sends to an Approver. Preparer-to-Approver transmission is not final filing.
Pre-commencement expenses and first accounts over twelve months
Only qualifying revenue expenses within one year before the deemed commencement date are covered by this FAQ: C-S Part B Box 8, or included in Lite Box 2. For long first accounts, Part A shows the full financial-statement period; Part B separates relevant YAs and Part C uses the whole period. For 1 April 2024–31 December 2025, attribute adjusted profit/loss before other deductions to YA 2025 and YA 2026, generally no more than twelve months per YA. Time apportionment is allowed if direct identification is unavailable.
Why no outstanding YA 2026 filing appears
A 2025 incorporation normally first receives a return for YA 2027. If first accounts close in 2025 and business commenced or income arose then, request the YA 2026 return using Request for Income Tax Return for Newly Incorporated Companies; the service usually opens in May. Existing companies may have a waiver: Account → Update Corporate Profile/Contact Details may show No business done. If business or income restarted in 2025, use Recommencement of Business with requester name/UEN, email/phone, the earlier of restart or other-income date, and any changed principal activity/effective date with ACRA profile. For a one-off income transaction followed by continued dormancy, send IRAS an explanatory letter, accounts and tax computation rather than requesting the return.
SCTP reviewer information and responsibility
From YA 2021 IRAS uses reviewer information for taxpayer profiling. Where a return was reviewed by an SCTP Accredited Tax Advisor or Practitioner for Income Tax, disclose name and membership number: three letters plus four digits, such as ATA1234 or ATP6789; IRAS may verify them. Choose No if not reviewed by such a member, or their required particulars are unavailable. Review never transfers the company’s accuracy/completeness responsibility.
All reviewer scenarios
Director prepares/reviews: director. Accounts officer prepares and director reviews: director. Finance manager reviews and director endorses: finance manager or director. Agent staff prepare and agent tax manager reviews before director submits: agent tax manager. Same review before agent partner endorses: tax manager. Company files the agent-reviewed outcome unchanged: agent tax manager; if company personnel instead review and change its tax position, name that company reviewer. For multiple accredited reviewers disclose any one reviewer’s full name and membership number.
Pre-filled capital allowances, losses and donations
Since YA 2018 the return pre-fills unutilised capital allowances, losses and donations brought forward, plus current approved donations. Brought-forward values follow the last preceding-YA assessment even under objection/review; if that assessment is not finalised, the FAQ uses the amounts declared in the preceding return. Enter the company’s different figures, including amounts under objection, in Company’s Declaration. Update a non-SGD functional currency in Corporate Profile first.
Donation mismatches and financial-year changes
Deductions follow the financial period and IPC-submitted information in View Donations. A later IPC receipt date may shift the deduction to a different YA. Missing UEN should be corrected with the IPC; IRAS amends on receiving its revised record. For visible donations update financial year end and functional currency before filing. A non-SGD currency update permits a higher SGD-equivalent donation entry. A saved draft retains the old year-end’s donation data: after IRAS records reflect the ACRA change, delete that draft and begin a new copy.
Drafts, approvals and inactivity
Save Draft is available before submission. The PDF says drafts or pending-approval versions are retained for twenty-one days or until 30 November, whichever is later; retention does not extend the filing deadline. To let a Preparer amend a pending return, the Approver retrieves and saves it as a draft, or makes the amendment directly. No alert is sent to the Approver: the Preparer must inform them. Fifteen minutes of inactivity triggers a two-minute response prompt before logout.
Submission failures and required declaration
Check the IRAS Bot or Corporate Tax → View Corporate Tax Filing Status. If Ready to File, clear cache, close active applications and retry. Persistent problems go through myTax Mail with date/time, company UEN/ID and login person, error stage, OS, browser/version and message/screenshot. The PDF’s XP/Vista and Firefox 2 examples are historical, not supported-software recommendations. Approvers must tick the full-and-true-income declaration, enter their designation and supply contact name, designation and phone before Submit.
Acknowledgement, retrieval and correction
A successful filing displays an acknowledgement; use Save as PDF/Print at the top. If absent, check filing status rather than assuming submission. Filing status and a retrievable acknowledgement become available after three working days; the latter is under Notices/Letters → Corporate Tax. To correct an already-filed return, use Revise/Object to Assessment with financial statements, tax computation and supporting schedules, following the separate NOA-objection guidance.
Official source
This article independently explains the substantive contents of the official PDF, including the relevant conditions, procedures and annexes. The linked document remains the authoritative source for its original wording, and later changes should be checked separately.
Read the official PDF ↗