Accounting Solutions Singapore Editorial Team · Last reviewed 25 October 2026
IRAS audits GST-registered businesses on a risk basis. IRAS says that being selected does not necessarily mean you have made a mistake. In FY2025/26 it completed more than 2,700 GST audits across many industries. Whether yours goes smoothly depends mostly on one thing: can your records answer IRAS’s questions quickly and consistently? This page explains how an audit runs, what IRAS checks, how to prepare, and what to do if you find an error.
At a glance
| Question | Short answer |
|---|---|
| What is an audit? | A review of whether GST has been accounted for properly and reported correctly in your GST returns |
| How is it carried out? | By email, letter and telephone interview. IRAS may also visit your premises or ask to meet key staff. |
| What will IRAS ask for? | Information about your business, sales and purchases listings, supporting documents, and completed self-review checklists |
| How long does it take? | IRAS says most GST audits are completed within 12 months |
| How do you hear the result? | In writing |
| If you disagree? | You can file a written objection. For an assessment, within 30 days of the Notice of Assessment. |
If IRAS has written to you
- Note the date of the letter and any date IRAS has given for your reply.
- Read what is being asked before sending anything. Check which GST periods and which issues it covers.
- Check who is asking. An officer visiting your premises carries an IRAS authority pass.
- Reply fully and accurately. IRAS expects timely, complete and accurate replies, and says that full disclosure of any irregularities or omissions should be made at the earliest possible time. Under section 66 of the GST Act it is an offence to obstruct or hinder the Comptroller or an officer in their duties.
- Write to IRAS clearly. IRAS encourages you to use myTax Mail, which is secure. IRAS’s guidance on writing to it (published for corporate income tax) asks you to give your company’s name and tax reference number, a contact person’s name and phone number or email, and a clear subject line. If you know the officer in charge of your case, name them. When you send documents in reply to an IRAS query, quote the reference number shown on IRAS’s letter.
What IRAS checks
IRAS says an audit covers whether your supplies are classified correctly, whether GST was properly charged and accounted for, whether input tax was claimed correctly, and whether the values of supplies, purchases and taxes in your returns are complete. IRAS may also ask customers, suppliers or banks to confirm that your transactions are genuine, and ask you to show how transactions are recorded in your system.
IRAS currently focuses audits on four areas:
- Missing Trader Fraud arrangements
- Businesses making low-value GST refund claims
- Sale of non-residential property
- Under-declaration of supplies by sole proprietors
Input tax
IRAS lists the conditions for claiming input tax. In summary, all of these must be met:
- The goods or services were supplied to you, or imported by you.
- They are used, or will be used, for your business.
- Local purchases are supported by a valid tax invoice addressed to you, or a simplified tax invoice, when you claim.
- Imports are supported by an import permit showing you as the importer, plus documents such as the supplier’s invoice and transport documents.
- The input tax is directly attributable to taxable supplies (or out-of-scope supplies that would be taxable if made in Singapore).
- The claim is not disallowed under Regulations 26 and 27 of the GST (General) Regulations.
- You took reasonable steps to ascertain that the supply was not part of a Missing Trader Fraud arrangement.
In its audits of low-value refund claims, IRAS names these common errors: input tax claimed by a dormant business with no taxable supplies; claims without a tax invoice or import permit addressed to the business; claims on disallowed expenses such as motor car and medical expenses; and claims on private expenses. On that last point, IRAS is clear that even if you run your business from home, you cannot claim input tax on housing-related expenses.
Zero-rated sales
Not every overseas sale is zero-rated. For exports, IRAS expects proper export documents. Where a business could not produce them, IRAS standard-rated the sales and recovered the GST.
Example (illustration only). ABC Pte Ltd zero-rates its sales of goods to overseas customers. During a review it cannot produce the export documents for several shipments. IRAS is then not satisfied the goods left Singapore, so it can treat those sales as standard-rated and recover the GST at the prevailing rate.
Other points IRAS has raised in recent audits
- Credit notes should be issued only to correct a mistake or for a genuine adjustment to an earlier supply, and should be supported by the original tax invoice. In one IRAS case, credit notes issued for internal cost adjustments, with no link to any original sale, led to output tax being understated.
- Transfers between related companies are not automatically ignored for GST. Where ownership of goods passes between separate legal entities, check whether it is a taxable supply.
- Reconciliation. IRAS says differences between the revenue in your financial statements and the taxable supplies in your GST returns can point to reporting errors and should be looked into promptly.
Missing Trader Fraud
Since 1 January 2021, you are not entitled to input tax on a purchase you knew, or should have known, was part of a Missing Trader Fraud arrangement. IRAS may impose a 10% surcharge on the input tax denied. IRAS suggests three steps: assess the risks in your transactions, carry out due diligence checks on new arrangements, and act on what you find.
IRAS lists risk indicators including high-value deals from a newly established supplier, pre-arranged deals, consistent or pre-determined profit margins whatever the quantity, very low commercial risk (for example, no need to hold inventory), and requests to pay offshore or third-party accounts.
You must keep a record of the steps you took: the risks you assessed, the checks you performed, and what you did in response.
What IRAS will ask you to provide
- Information about your business, such as business arrangements and how you run it
- Sales and purchases listings that support the figures in your returns
- Supporting documents for transactions, such as invoices and export documents
- Self-review checklists, for example the form for pre-registration input tax claims or bad debt relief
Listings given to IRAS must be in Excel, Access, or a delimited text file such as CSV (for data listings), or Word or PDF (for non-data listings). They must include:
| Sales listing | Purchases listing |
|---|---|
| Invoice date | Invoice date |
| Invoice number | Invoice number |
| Name of customer | Name of supplier |
| Description | Supplier’s GST registration number |
| Invoice amount excluding GST | Description |
| GST, if applicable | Invoice amount excluding GST |
| Destination of goods, if applicable | GST, if applicable |
How we prepare a business
- Reconcile your GST returns to your books, period by period.
- Sample your input tax claims against invoices and import documents.
- Review the evidence for zero-rated sales of exports and international services.
- Check your Missing Trader Fraud records and note any gaps.
- Prepare written explanations for any differences, so replies are ready before IRAS asks.
If we find an error, we explain your options below and prepare the correction.
If you find an error
You can correct it yourself, and you should do so as soon as you find it.
Which form. IRAS allows a concession: you may adjust the error in your next GST F5 if both of these are true.
- The net GST in error across all affected periods is not more than S$3,000. This is the additional output tax (Box 6) less the additional input tax (Box 7).
- The errors in all other boxes, except Boxes 6, 7 and 12, are not more than 5% of the total value of supplies (Box 4) for each affected period. If you made no supplies, the 5% is measured against taxable purchases (Box 5).
If you do not meet both, file a GST F7. Request it in myTax Portal and e-file it within 14 days, or it expires. The F7 is the same as an F5: enter the revised full figures for every box, not just the adjustment. It replaces the return filed earlier. Errors must be corrected within five years of the end of the accounting period.
Penalties and the Voluntary Disclosure Programme. IRAS may reduce or remove penalties if you disclose an error voluntarily and meet its conditions. The disclosure must be timely, accurate, complete and self-initiated, and you must cooperate fully and pay, or arrange to pay, the tax and any penalty.
- Within one year of the statutory filing deadline (for GST, one month after the end of the accounting period): no penalty.
- After that: a flat 5% of the tax undercharged.
- Anything else: IRAS can penalise up to 200% of the tax undercharged.
“Timely and self-initiated” means before you receive an IRAS query, or before IRAS notifies you that an audit or investigation has started. If you are already under query or audit, the errors you disclose must not be directly related to its scope. A disclosure made after a notice of audit can still qualify when it covers a different matter.
IRAS says the reduced penalties do not apply where there was wilful intent to evade tax.
Example (illustration only). ABC Pte Ltd finds it claimed input tax on two invoices addressed to a director personally, and on utilities for the director’s home. The net GST error across the affected periods is S$4,500, which is over S$3,000, so ABC files a GST F7. If ABC discloses before IRAS queries it, meets the conditions, and does so within one year of the statutory filing deadline, no penalty applies. After that, the flat 5% would be S$225 (5% of S$4,500).
Extra GST paid after the due date can also attract a 5% late payment penalty. IRAS says that if you file the F7 within one year of the original statutory filing deadline and meet the conditions, no late payment penalty is imposed on the additional GST disclosed.
After the audit
IRAS tells you the outcome in writing. It may raise assessments to adjust your reported figures, and may impose penalties on the additional tax. The letter explains the basis of any adjustment, the reasons for any penalty and its amount, and what to look out for to comply better. For an incorrect return, IRAS says businesses may be penalised up to 200% of the tax undercharged or over-claimed, and may be liable to a fine and imprisonment. Fraud is treated more severely.
If you disagree. You can object to matters listed in section 49(1) of the GST Act, which include assessments, refund claims and input tax allowable. A valid objection is in writing to the Comptroller of GST, states the detailed reasons, is made within the time limit, and is signed and dated. An objection to an assessment must be made within 30 days of the Notice of Assessment.
If you still disagree with the Comptroller’s decision, you can appeal in writing to the GST Board of Review within 30 days of the decision, then lodge a petition of appeal stating your grounds within a further 30 days. The burden is on you to prove the Comptroller’s decision is wrong. The Ministry of Finance has the format for a notice of appeal.
Reviewing your GST position before IRAS does
IRAS runs two voluntary programmes that suit different businesses.
- Assisted Self-help Kit (ASK). IRAS describes ASK as a self-assessment package to help you manage GST compliance. If you carry out an ASK annual review, you have a grace period of one year from the statutory filing deadline of the last GST return in the period you reviewed, to disclose errors under the Voluntary Disclosure Programme.
- Assisted Compliance Assurance Programme (ACAP). ACAP is a voluntary, risk-based review of a business’s GST controls, carried out by an independent ACAP Reviewer. IRAS says it suits businesses with complex structures and business models and large volumes of transactions. To be eligible you must have been GST-registered for at least three years, have an unqualified auditor’s opinion on your latest financial statements, not be under an IRAS GST audit, and have good compliance records. A successful review earns ACAP Premium status (five years) or ACAP Merit status (three years). IRAS lists benefits including a step-down of its GST compliance activities unless significant anomalies are noted, and faster GST refunds if there are none. It also offers a one-time waiver of penalties for non-fraudulent errors disclosed under the first ACAP, if the review is completed and status attained within 15 months of IRAS accepting your participation.
Record-keeping
- How long: at least five years. Companies and LLPs must also keep records for five years after they are struck off, dissolved or wound up.
- What: source documents (receipts, invoices, vouchers, contracts), bank statements, accounting ledgers and schedules, and your Missing Trader Fraud records. This applies whichever payment channel you use, including PayNow, Buy Now Pay Later platforms, marketplaces and delivery platforms.
- Electronic records are fine without IRAS approval, if you have internal controls for integrity, completeness, accuracy, availability and reliability. If source documents are kept electronically, you do not need to keep the paper copies.
- Bank statements alone are not enough. IRAS expects source documents and accounting records too.
- If records are missing, IRAS may estimate your revenue and disallow expense claims, capital allowances and GST input tax.
- Failing to keep records is an offence under the GST Act: a fine of up to S$5,000 and/or imprisonment of up to six months, rising to S$10,000 and/or three years on a later conviction.
- IRAS also advises keeping business and personal bank accounts separate.
For more, see our guide to conditions for claiming GST input tax.
Who this is for
- GST-registered businesses that have received an IRAS notice or query
- Businesses that want a check after fast growth, a change of bookkeeper, or a first year of exporting
- Businesses that suspect a past GST return is wrong
How this fits with our other services
- GST compliance and filing: the regular returns, so there is less to untangle later
- Correcting GST errors (Form F7): how a correction is filed
- Bookkeeping: the records an audit relies on
- GST services overview
Questions we get asked
IRAS has written to us. What should we do first? Note the date of the letter and any reply date it gives, and read exactly what is being asked. Contact us before sending documents so the reply covers what was asked and no more.
Does an audit mean we did something wrong? No. IRAS says audits are risk-based and that it does not assume a selected business has made errors.
Can IRAS contact our customers, suppliers or bank? IRAS says it may seek confirmation from them to check that the transactions in your returns are genuine.
Should we correct an error before IRAS asks? Usually yes. A disclosure made before a query, within one year of the statutory filing deadline and meeting IRAS’s conditions attracts no penalty. After that the flat 5% applies.
Do small mistakes always need an F7? No. Within IRAS’s concession you can adjust in your next F5. IRAS also says no F7 is needed for an error only in Box 13 (revenue), or for rounding to the nearest dollar in the non-tax boxes. See our page on correcting GST errors.
How long does an audit take? IRAS says most GST audits are completed within 12 months. It depends on how complex your affairs are and how quickly you and your representatives cooperate.
How long do we keep GST records? At least five years. Companies must keep them for five years after being struck off or dissolved.
Ask for a GST health check
Tell us your GST filing frequency, the periods IRAS has asked about (if any), and whether you export. We’ll tell you what we would check first. Ask for a GST health check.
Sources
- IRAS, Overview of audits by IRAS
- IRAS, Current Areas of GST Audits
- IRAS, Recent GST Audits by IRAS (FY2025/26 case highlights)
- IRAS, Audits and Investigations on Missing Trader Fraud
- IRAS, Correcting errors made in GST return (filing GST F7)
- IRAS, Late Filing or Non-Filing of GST Returns (F5/F8)
- IRAS, e-Tax Guide: IRAS’ Voluntary Disclosure Programme (Thirteenth Edition, 30 January 2026)
- IRAS, e-Tax Guide: Record Keeping Guide for GST-Registered Businesses (Twelfth Edition, 30 January 2026)
- IRAS, Record Keeping Requirements
- IRAS, Best Practices When Writing to IRAS
- IRAS, Object to Audit Assessment
- IRAS, Assisted Compliance Assurance Programme (ACAP)
This page is general information as at the date above, not legal, regulatory or professional advice. Rules and penalties change, so please take advice on your own circumstances before acting.