Every Singapore company files a corporate income tax return by 30 November — the only question is which form. It goes by revenue and complexity, and for most small companies the answer is the simplest one:
The decision in one list
- Form C-S (Lite) — revenue ≤ S$200,000 and you meet the C-S conditions: six fields, the friendliest return IRAS makes.
- Form C-S — revenue ≤ S$5 million, Singapore-incorporated, income taxed at 17%, and no claims for carry-back relief, group relief, investment allowance or foreign tax credit.
- Form C — everyone else, with financial statements and tax computation submitted.
"Don't submit" ≠ "don't prepare"
C-S filers skip submitting the financial statements and tax computation — but IRAS requires you to prepare them and keep them ready. If a query comes, "we never made statements" is not an answer; it's an offence. The full set is: unaudited financial statements, an IRAS-format tax computation with supporting schedules, and the records behind them — kept five years.
The annual rhythm for a small company
- Within 3 months of year end — ECI, unless waived (see our ECI guide).
- 30 November — Form C-S / C-S (Lite) / C for the financial year that ended last calendar year.
- Within 1 month of the NOA — payment, or GIRO instalments.
Bookly's job is exactly this: the figures Form C-S asks for, plus the financial statements and IRAS-format computation you must keep behind them — produced from your bank statements and receipts. Start free.
Eligibility rules per IRAS as at June 2026. General information, not tax advice.