Singapore: If your claim is reviewed

An IRAS review has deadlines: a Notice of Objection within two months of the Notice of Assessment, and an appeal within 30 days of a Notice of Refusal to Amend. Tax assessed is due one month from the Notice of Assessment even while an objection is pending. Before you reply to anything, read your engagement letter to see what help it provides, tell your adviser the same day, and take advice from someone who can see the letter and the claim. This page describes the process in general terms from IRAS's own guidance; it is not a guide to handling a review, and nothing here replaces advice on your own case.

IRAS reviews corporate income tax returns on a risk basis. Companies with straightforward affairs have their declarations accepted upfront, with a small percentage reviewed under compliance programmes; if your company is selected, you can expect an enquiry letter from IRAS, and IRAS may request supporting documents to substantiate the declarations. Companies with more complex affairs get in-depth reviews. After a completed assessment has been issued, IRAS may review the return again if new information comes to its attention.1Source 1IRAS, After filing Form C-S/ Form C-S (Lite)/ Form C (29 May 2026). IRAS also conducts both risk based and random audits across all industries, and it says it is important for companies to maintain adequate documentation of qualifying activities and expenditures.2Source 2IRAS, Getting companies to comply (17 July 2026).

No supporting documents go in with an R&D claim. The company must prepare and keep proper documentation from the start of the R&D project, rather than after the event, and present it on request. Companies that file Form C-S keep the completed R&D claim form and submit it when asked.3Source 3IRAS, Research & Development (R&D) Tax Measures (13 August 2026). The your responsibility page explains why the company holds these records, and the ownership of records clause is where to look if the adviser holds some of them.

IRAS has set up a Technical Advisory Panel to advise it on R&D claims, and may also consult IPOS International in its review. A case is referred to the Panel when the company specifically requests it, or when IRAS rejects the claim after two rounds of review and the company wishes to pursue it. A Panel meeting is for clarifications on the claim, not an arbitration, and with the Panel's technical advice IRAS makes the final decision.3Source 3IRAS, Research & Development (R&D) Tax Measures (13 August 2026).

If tax adjustments are made in the course of a review, IRAS issues an amended or additional Notice of Assessment.1Source 1IRAS, After filing Form C-S/ Form C-S (Lite)/ Form C (29 May 2026). If the deduction is reduced, the penalty rules on the your responsibility page apply. The tax is due one month from the Notice of Assessment even if you object. IRAS charges a 5% late payment penalty on tax unpaid by the due date, and a further 1% a month, up to 12%, if it stays unpaid 60 days after that.4Source 4IRAS, Late payment or non-payment of Corporate Income Tax (10 August 2026).

A Notice of Objection in writing, with precise grounds, must be filed within two months from the date of service of the Notice of Assessment, through the Revise/ Object to Assessment digital service. If IRAS does not agree, it issues a Notice of Refusal to Amend. You can file a Notice of Appeal to the Income Tax Board of Review within 30 days of that notice. The Board's decision is final where no question of law is involved; on a question of law there is an appeal to the General Division of the High Court.1Source 1IRAS, After filing Form C-S/ Form C-S (Lite)/ Form C (29 May 2026). 5Source 5IRAS, Corporate Income Tax: Objection and Appeal Process, e-Tax Guide (Fourth Edition) (30 January 2026), paragraphs 2.1, 2.5, 4.3.1, 6.1 and 6.2. Each of these has a deadline, and the choice is a matter for advice.

What your adviser must do depends on the engagement letter, which is why the review and audit support clause matters before you sign. In a review, the useful things an adviser does are these.

• Produce the project documentation and the R&D claim form quickly and in order.
• Help the company explain how the work meets the three requirements in the Act, with the people who did the work.
• Consider with you whether to ask for a Panel referral.
• Correct any error through the Voluntary Disclosure Programme before an audit notice, if that is the right course on advice.
• Tell you plainly what an amended assessment means and what your options are, including the two month objection deadline.

Nothing an adviser does moves the tax or penalty off the company.6Source 6IRAS, Penalties for errors in tax returns (2 March 2023); Income Tax Act 1947 section 95. If the adviser's help is charged by the hour, agree an estimate and a ceiling before the work starts. The companies under review page and the claim reduced on review page cover the fee side.

• Your responsibility and complaints about an adviser in Singapore
• How do you handle a tax authority review? and is review support included?
• Getting independent advice

Sources

1. IRAS, After filing Form C-S/ Form C-S (Lite)/ Form C (29 May 2026).    Back
2. IRAS, Getting companies to comply (17 July 2026).  Back
3. IRAS, Research & Development (R&D) Tax Measures (13 August 2026).   Back
4. IRAS, Late payment or non-payment of Corporate Income Tax (10 August 2026).  Back
5. IRAS, Corporate Income Tax: Objection and Appeal Process, e-Tax Guide (Fourth Edition) (30 January 2026), paragraphs 2.1, 2.5, 4.3.1, 6.1 and 6.2.  Back
6. IRAS, Penalties for errors in tax returns (2 March 2023); Income Tax Act 1947 section 95.  Back