GST Audit in Singapore: What IRAS Checks, the Errors It Finds and How to Respond (2026)
By Lucas Seah, Founder of Excellence Singapore Group | Last Updated: October 2026
A GST audit in Singapore is IRAS checking that your GST returns are correct and complete: the GST you charged on sales (output tax), the GST you claimed back on purchases (input tax) and the values you reported. IRAS says being selected “does not necessarily mean that you have made a mistake”, and most GST audits finish within 12 months.
If IRAS has told you it is auditing your GST, three things matter from day one. Send exactly what IRAS asks for, in the format it asks for. Keep every answer accurate and complete. Take advice before you correct anything, because only errors not directly related to the audit’s scope can still qualify for the reduced penalties of a voluntary disclosure.
GST audits are common. IRAS completed more than 2,700 GST audits in its 2025/2026 financial year and recovered S$226 million, including penalties. The most common problem it finds is incorrect input tax claims.
Short on time? Jump to what to do first, what IRAS asks for or the penalties.
Key Takeaways
- IRAS picks businesses for GST audits mainly on risk, using data analytics within each industry, plus some audits to test general compliance. Being picked is not an accusation.
- Expect requests for sales and purchases listings in IRAS’s format, plus invoices, export documents and explanations of how the business runs. IRAS may visit, interview staff and check with your customers, suppliers and bank.
- Incorrect input tax claims are the most common error IRAS reports, from blocked expenses such as motor cars and staff medical costs to private expenses and claims without proper tax invoices.
- Penalties for an incorrect return go up to 200% of the tax undercharged, and deliberate evasion carries, on conviction, 3 times the tax plus a fine, jail or both.
- IRAS can generally assess up to 5 years after the end of a GST accounting period, with no time limit for fraud or wilful default, and you can object to an audit assessment within 30 days of the Notice of Assessment.
What is a GST audit in Singapore?
It is IRAS’s review of the GST your business has charged, collected and claimed. One key check is whether each sale was classified correctly: standard-rated (GST at the standard rate, now 9%), zero-rated (GST at 0%, mainly for exports) or exempt (no GST, for example on the sale or lease of residential property). IRAS also checks that input tax was claimed correctly and that the values in your returns are complete.
A GST audit is different from your company’s statutory audit of its financial statements, and from an IRAS investigation into suspected evasion. Our guide to IRAS audits in Singapore explains how a review, an audit and an investigation differ, and covers income tax audits too.
What should you do when the audit notice arrives?
- Note the deadline and the scope: the reply date, the GST periods named and what IRAS asks for. Unsure the request is genuine? Our guide to the first 7 days after an IRAS letter shows how to check.
- Reconcile each period before you send anything: revenue in your accounts against supplies in your GST returns, and input tax claimed against purchase invoices on file.
- Prepare the listings in IRAS’s format, with the invoices, import permits and export documents behind them.
- Take advice on any errors you find. Raise errors inside the audit’s scope with IRAS early; errors outside it may still qualify as a voluntary disclosure.
- Decide who deals with IRAS, and brief the staff it may want to interview.
How does IRAS choose businesses for a GST audit?
IRAS audits businesses across a broad range of industries. Within each industry it generally uses a risk-based approach, supported by data analytics, and it also runs periodic audits to check the general level of compliance.
Refund claims draw particular attention. In 2025, IRAS audited more than 1,300 businesses making GST refund claims and recovered over S$100 million in taxes and penalties. IRAS also accepts tip-offs, and a reward based on 15% of the tax recovered, capped at S$100,000, may be given at the Comptroller’s discretion where the information leads to a recovery.
IRAS’s four current focus areas
IRAS says it is currently focusing GST audits on four areas:
- Missing Trader Fraud arrangements, schemes that use fictitious transactions between a network of businesses to claim GST refunds or avoid tax.
- Businesses making low-value GST refund claims.
- Sales of non-residential property, where common mistakes include not charging GST on the sale, accounting for GST on option fees too late and missing GST on transfers made without payment.
- Under-declaration by GST-registered sole proprietors, who must account for GST on the turnover of all their businesses, not only one. Our GST registration guide explains how a sole proprietor’s businesses are combined.
What happens during a GST audit?
IRAS can run an audit by email, letter and telephone interview, or visit your premises and ask to meet key personnel and staff. Officers who visit carry an IRAS authority pass. To confirm an officer’s identity, call IRAS on 6351 2044 or 6351 2046.
What IRAS asks for
IRAS lists what it will ask for. The second column shows what each item proves.
| What IRAS asks for | What it shows IRAS |
|---|---|
| Information on your business | How the business runs and what it supplies, so IRAS can judge the right GST treatment |
| Sales listings | That every supply and its GST is in your returns: invoice date and number, customer, description, amount before GST, GST and, for goods, where they went |
| Purchases listings | That input tax claims match real purchases: the same details, plus each supplier’s GST registration number |
| Invoices, import permits and export documents | That input tax is supported by documents in your name, and that zero-rated goods really left Singapore |
| Completed self-review checklists | That special claims, such as pre-registration input tax or bad debt relief, meet IRAS’s conditions |
Source: IRAS, Overview of audits by IRAS. Listings go to IRAS as an Excel, Access or delimited text file, or as a Word or PDF document, and the same page has Excel templates for both listings. Read October 2026.
IRAS may also ask your customers, suppliers or bank to confirm that the transactions in your returns are genuine, and you may need to show how transactions are recorded in your accounting system. IRAS has the legal power, under section 84 of the GST Act, to obtain information, documents and computer records.
Your obligations during the audit
IRAS expects full access to your premises, records and documents, a room or working space for its officers, access to staff who run the processes, permission to take copies, and timely, complete and accurate answers. It also asks you to be truthful and to disclose any irregularities or omissions at the earliest possible time. Hindering or obstructing an officer is an offence under section 66 of the GST Act, punishable on conviction with a fine of up to S$10,000, jail of up to 12 months, or both.
Never send IRAS a document or an answer you cannot stand behind. In May 2026, an accountant was sentenced to 30 weeks’ jail for giving IRAS fictitious invoices and transaction listings during a GST audit. IRAS said that deliberately giving its officers false information carries a penalty of 3 times the tax undercharged and a fine of up to S$10,000, jail of up to 7 years, or both.
How long does a GST audit take, and how does it end?
IRAS says most GST audits are completed within 12 months. Progress depends on how complex the business is and how well the business and its tax representatives cooperate. IRAS then tells you the outcome in writing. If it raises an assessment, the letter explains the basis of each adjustment, the reasons for any penalty and its amount, and the issues to watch in future.
What GST errors does IRAS find most often?
IRAS says the most common mistake its GST audits find is incorrect input tax claims, and that it recovers more than S$18,000 in GST and penalties, on average, from each business that makes them. The errors IRAS highlights in its audit focus areas and case studies include:
- Blocked expenses. Input tax cannot be claimed on motor car costs, club subscriptions, benefits for staff’s family members, or staff medical expenses and medical or accident insurance (Regulations 26 and 27 of the GST (General) Regulations). The exceptions are narrow, such as insurance required under the Work Injury Compensation Act.
- Private and household expenses. Food and drink for family, or utilities and maintenance fees for a home, cannot be claimed, even if the business is run from home.
- Claims without the right document. Input tax must be supported by a tax invoice or import permit addressed to the business, or a simplified tax invoice where allowed. IRAS warns that tax invoices are necessary but not sufficient on their own: the purchase behind them must be real.
- Dormant businesses claiming refunds without making taxable supplies.
- Zero-rated exports without proper export documents. If IRAS is not satisfied that the goods left Singapore, it treats the sale as standard-rated and recovers the GST at the rate that applied at the time.
- Credit notes not linked to a genuine adjustment of an earlier supply, and transfers of goods between related companies treated as internal when GST should have been charged.
In three of the four cases IRAS highlighted for its 2025/2026 financial year, GST was missed on sales:
Our guide to correcting GST errors with a GST F7 explains how to fix mistakes like these in past returns.
What penalties can IRAS impose after an audit?
IRAS says businesses that file incorrect GST returns may be penalised up to 200% of the tax undercharged. The GST Act sets the penalties below for a conviction in court, and the penalty after an audit can be far lower: in one 2025/2026 case, IRAS recovered S$8.1 million of understated output tax and imposed a penalty of S$49,000.
| Situation | Penalty |
|---|---|
| Incorrect return (section 59(1)) | On conviction, a penalty equal to the tax undercharged (100%) |
| Incorrect return, negligent or without reasonable excuse (section 59(2)) | On conviction, a penalty of double the tax undercharged (200%), plus a fine of up to S$5,000, jail of up to 3 years, or both |
| Wilful evasion (section 62) | On conviction, 3 times the tax undercharged, plus a fine of up to S$10,000, jail of up to 7 years, or both |
| Input tax claimed on purchases you should have known were part of Missing Trader Fraud | The input tax is denied, with penalties and/or a 10% surcharge on the input tax denied |
| The same error disclosed voluntarily before IRAS’s query or audit, meeting the VDP conditions | No penalty within 1 year of the return’s statutory filing deadline, then a flat 5% of the GST undercharged |
Sources: GST Act section 59 and section 62; IRAS current focus areas for audits and voluntary disclosure page. Read October 2026.
Late payment of the additional GST carries its own penalties; our guide to IRAS penalty waivers covers when IRAS may waive or reduce them.
How far back can a GST audit go?
IRAS generally cannot raise a GST assessment more than 5 years after the end of the accounting period concerned. There is no time limit where there has been fraud or wilful default. Businesses must keep their GST records for at least 5 years from the end of the accounting period, so expect IRAS to ask for records from any period it can still assess.
Can you still disclose other errors during the audit?
Yes, for errors outside the audit’s scope. A voluntary disclosure normally has to reach IRAS before it queries you or tells you an audit has started, but IRAS’s e-Tax Guide on the programme says errors not directly related to the audit’s scope can still qualify. Errors inside the scope do not get the reduced penalty, but IRAS asks you to disclose them at the earliest possible time, and says it treats disclosures of past mistakes as a mitigating factor.
In its audits of businesses making low-value GST refund claims, IRAS may also require businesses to review their past GST returns and disclose any errors found. Our guide to the IRAS Voluntary Disclosure Programme explains the conditions and the reduced penalties.
What if you disagree with the audit outcome?
You can object. A valid GST objection must be in writing to the Comptroller of GST, state detailed reasons, be signed and dated, and be made within 30 days of the Notice of Assessment. If you disagree with IRAS’s decision on the objection, you can appeal to the GST Board of Review within 30 days of the decision, and lodge a petition of appeal within a further 30 days. On appeal, the burden is on you to prove IRAS’s decision wrong, so build your evidence from the objection stage.
How can you lower your GST audit risk?
IRAS’s own advice is practical: staff with sound GST knowledge, good record-keeping, a computerised accounting system, good internal controls and regular reviews. Its case notes add one more: reconcile the revenue in your financial statements with the supplies in your GST returns, because differences can point to errors. Two IRAS programmes go further:
- ASK annual review. The Assisted Self-help Kit is IRAS’s self-assessment package for reviewing your own GST returns, and errors it finds can then be disclosed voluntarily. An ASK review is your own check, not an IRAS audit. Businesses applying for or renewing the Major Exporter Scheme need an ASK review performed or certified by an SCTP-accredited GST professional, unless they are on ACAP, which our MES guide explains.
- ACAP. The Assisted Compliance Assurance Programme is open to businesses that, among other conditions, have an acceptable GST control framework, have been GST-registered for at least three years, have an unqualified auditor’s opinion on their latest financial statements, have good compliance records, are not under a GST audit and engage a qualified ACAP reviewer. ACAP status brings a step down in IRAS’s GST compliance activities unless significant anomalies are noted, and a one-time penalty waiver for disclosing past non-fraudulent errors found in the first ACAP review.
How we help with GST audits
Excellence Singapore Group’s tax team, which brings accreditation from the Singapore Chartered Tax Professionals (SCTP) in both income tax and GST, handles IRAS letters and audits as well as GST filing. When IRAS opens a GST audit, we:
- Read the notice with you and agree the strategy: what IRAS is looking at, which periods, and what the records will show.
- Prepare the listings, schedules and replies IRAS asks for, and attend meetings and field visits with you.
- Check for other errors and sort them: those outside the audit’s scope can still be disclosed at reduced penalties, and those inside it are best raised with IRAS early.
- Review the outcome and prepare an objection where the facts support one.
- Fix the cause afterwards, through our accounting team or an ASK annual review.
Fees are quoted after we review the notice. If IRAS has given you a deadline, tell us the date when you contact us.
Frequently Asked Questions
What happens in a GST audit?
IRAS checks that your sales are classified correctly, GST was charged and accounted for, input tax was claimed correctly and your figures are complete. It asks for sales and purchases listings, invoices and export documents, and may interview staff, visit your premises and check with customers, suppliers or banks. It then explains the outcome and any adjustment in writing.
How long does a GST audit take?
IRAS says most GST audits are completed within 12 months. How long yours takes depends on how complex the business is and how quickly and completely you and your tax representatives respond. Sending listings in IRAS’s format, with supporting documents ready, reduces the back-and-forth that slows an audit down.
What triggers a GST audit in Singapore?
Mainly risk. Within each industry, IRAS selects businesses using a risk-based approach supported by data analytics, and it also audits some businesses to check general compliance. Refund claims draw extra attention, and IRAS accepts tip-offs. Its current focus areas are Missing Trader Fraud, low-value GST refund claims, sales of non-residential property and under-declaration by sole proprietors. Being selected does not mean IRAS assumes you have made errors.
Can my accountant handle a GST audit for me?
Yes. A tax agent or accountant can deal with IRAS for you, and IRAS says an audit’s progress depends partly on how well your tax representatives cooperate. Your business stays responsible for its returns and for everything sent to IRAS in its name, so give your representative complete records and check what goes out. IRAS also reminds taxpayers to take care in choosing the professionals they engage.
What is the penalty for an incorrect GST return?
Up to 200% of the tax undercharged, IRAS says. On conviction under section 59 of the GST Act, an incorrect return carries a penalty equal to the tax undercharged. Where the return was made without reasonable excuse or through negligence, the penalty is double the tax undercharged, plus a fine of up to S$5,000, jail of up to 3 years or both. Wilful evasion carries, on conviction, 3 times the tax plus a fine, jail or both.
Can I still disclose other GST errors during an audit?
Yes, if they are not directly related to the scope of the audit. IRAS’s e-Tax Guide on voluntary disclosure gives the example of a business under an input tax audit that disclosed an unrelated output tax error with a GST F7 and still qualified for reduced penalties. Errors inside the audit’s scope do not qualify, but IRAS still expects you to disclose them early, so take advice before you file anything.
Received a GST audit letter? Talk to us before you reply
The first reply sets the tone for the whole audit. Talk to us with the notice in hand, and we will tell you what IRAS is likely to look at and how to prepare.
