Singapore's R&D deductions follow the ordinary corporate tax calendar. There is no registration and no separate claim window: the deductions are claimed in the corporate income tax return by its filing due date, and the EIS cash payout is applied for after filing the return and before the filing due date. The dates are driven by the Year of Assessment, which follows the financial year in which the expenditure was incurred. This page sets out the calendar and the amendment rules.
Registration and notification
None. Singapore requires no registration or advance approval for R&D deductions or the EIS. Companies that want certainty before committing to a large project can apply for an advance ruling under the general advance ruling system, which is optional and carries a fee. The only timing condition specific to the scheme is the cash payout application window.
Claim deadline
| Item | Deadline | Late? |
|---|---|---|
| Estimated chargeable income (ECI) | Within 3 months of the financial year end, unless the company qualifies for the waiver | IRAS may issue an estimated assessment |
| Corporate income tax return (Form C-S, Form C-S (Lite) or Form C) | 30 November of the Year of Assessment | Late filing penalties and estimated assessments |
| R&D deduction claim | In the return, by 30 November | Can be added by objection or revised return within the statutory period |
| R&D claim form (where required) | With the return | IRAS may request it in a review |
| EIS cash payout application | After filing the return and before the filing due date, 30 November | No |
| Objection to an assessment | Within 2 months of the date of the notice of assessment | IRAS may accept a late objection at its discretion |
| Payment of tax | Within one month of the notice of assessment, or by GIRO instalments | Late payment penalties |
| Records | 5 years from the Year of Assessment | Not applicable |
The cash payout window is the trap. The application must follow the return and precede 30 November, so a company that files its return on 30 November cannot apply for the payout for that year. Filing the return in October leaves room.
Two practical points follow. First, the Year of Assessment convention means Singapore claims lag the spending by one to two years: a cost incurred in January 2025 is deducted in a return filed by 30 November 2026. Second, companies with financial years ending early in the calendar year have a long run-up, while those ending in December have only eleven months between year end and the filing due date, with the ECI in between. Planning the R&D claim into the ordinary tax calendar, rather than treating it as a separate exercise, avoids the November crunch.
Amendments and late claims
Before assessment. A company can revise its return through myTax Portal before IRAS assesses it, including to add or correct an R&D claim.
After assessment. A company that disagrees with the assessment, or wants to add a deduction it omitted, objects in writing within 2 months of the notice of assessment; IRAS may accept later objections where there are good reasons. Claims for an R&D deduction omitted from an earlier Year of Assessment can be raised within the period IRAS allows for revising an assessment, generally 4 years from the end of the Year of Assessment.
IRAS amendments. IRAS can raise additional assessments within 4 years from the end of the Year of Assessment, and at any time where there is fraud or wilful default.
Cash payout. The payout election cannot be made late or reversed once approved, and expenditure converted to cash cannot later be claimed as a deduction.
Calendar for a typical year end
For a hypothetical company, Bedok Analytics Pte Ltd, with a 31 December 2025 financial year end, so Year of Assessment 2026.
| When | What happens |
|---|---|
| January to December 2025 | R&D carried out; project records and timesheets kept |
| By 31 March 2026 | ECI filed |
| October 2026 | Form C filed with the R&D deductions and the R&D claim form |
| October to 30 November 2026 | EIS cash payout application, after the return and before the due date |
| Early 2027 | Notice of assessment; cash payout disbursed; tax paid within one month or by GIRO |
| Within 2 months of the notice | Objection window |
| To end of 2030 | IRAS's 4 year period for additional assessments |
| To end of 2031 | Records retained for 5 years from YA 2026 |
Common questions
Our financial year ends 30 June 2026. Which Year of Assessment? YA 2027, with the return due 30 November 2027.
We forgot to claim the enhanced deduction. Can we fix it? Yes, by objection within 2 months of the assessment, or by requesting a revision within the 4 year period.
Is there a separate deadline for the R&D claim form? No. It travels with the return and shares the 30 November date; IRAS may ask for it later if it was not filed.
Can we apply for the cash payout with the return? The application follows the return; file the return first, then apply, both before 30 November.
Related pages
Official sources
Educational content only, not tax advice. See the disclaimer.