What ASK Annual Review covers
The sixteenth edition of IRAS’s Assisted Self-Help Kit Annual Review Guide is dated 30 January 2026. ASK combines GST practices covering people, records, systems and controls; checks before filing a return; and an annual review of transactions and returns. Its annual review is a structured way to test accuracy, identify causes of errors and correct them. Businesses remain responsible for their returns even when bookkeeping or filing is outsourced.
When professional performance or certification is required
An ordinary voluntary review can be undertaken by the business or performed or certified by an Accredited Tax Adviser (GST), Accredited Tax Practitioner (GST), or provisional ATP (GST). Where ASK is a condition of applying for or renewing a GST scheme, the reviewer or certifier must be an ATA or ATP who has met SCTP’s practical and examination requirements. A provisional credential does not satisfy that scheme requirement. A suitably accredited employee can perform the review, or the business can prepare the work and obtain the required professional certification.
Schemes and additional requirements
The guide identifies ASK requirements for applications involving IGDS, AMCS, ACMT, ARCS, MES, AISS, 3PL and SWS, and for renewals of ACMT, MES, IGDS and SWS. Businesses should check the particular scheme’s requirements rather than treat ASK as a complete replacement for them. The general checklists do not cover every special-scheme condition, and an error affecting a scheme’s eligibility must also trigger a reassessment of that eligibility.
Voluntary disclosure and the longer grace period
For qualifying disclosures following ASK, the 5% late-payment penalty can be waived if the review is completed and errors disclosed within one year of the statutory filing date of the last GST return in the financial year or chosen 12-month review period. This differs from measuring the normal grace period separately for each return. The Voluntary Disclosure Programme’s qualifying conditions and exclusions still apply; outside the grace period its qualifying penalty treatment is generally 5% of the tax undercharged. Errors already discovered should be corrected immediately rather than held until an ASK exercise.
How the deadline works in examples
For a 31 December 2023 year-end with quarterly returns ending March, June, September and December, completing ASK and disclosure by 31 January 2025 can qualify for the waiver. If the financial year ends 30 November 2023 but returns end in the same calendar quarters, the returns ending December 2022 through September 2023 fall within the reviewed year; the last relevant filing date is 31 October 2023 and the corresponding disclosure deadline is 31 October 2024. A changed financial year-end may require changing the GST filing cycle.
Administrative concessions for common errors
Certain common errors disclosed through ASK can be dealt with under separate administrative concessions. Where the published concession covers the situation, the business may self-assess without first seeking approval, complete the required declaration, remedy the error and retain evidence for at least five years. Cases not covered require IRAS’s consideration. A concession for past errors does not authorise repeating the treatment in future unless expressly stated; false declarations, abuse or failure to remedy can result in enforcement.
Scope, records and group coverage
Prepare the year’s GST returns, transaction listings, accounts, invoices, credit and debit notes, customer-accounting documents, export evidence, import permits and records for relevant refund claims. GST groups must cover members in proportion to total supplies and purchases; divisional registrations must similarly cover all divisions. A member that is inactive and has only disregarded internal transactions can be excluded from sampling, but reverse-charge transactions are not disregarded for this purpose. Maintain documents showing all required checks even if using the business’s own templates.
Step 1: analyse the year’s GST trends
Review fluctuations in supplies, purchases and tax across the year, explaining business cycles, asset purchases or one-off transactions. Compare declared output and input tax with the amounts computed from reported values; the guide flags a negative S$10,000 output-tax difference and an input-tax difference above S$10,000 for reconciliation. Its output-tax table prints the expression “> -$10,000”, so the underlying calculation and under-accounting concern should be checked rather than mechanically treating that sign as a safe-harbour rule. A yearly taxable-purchases/total-supplies ratio above 1.2 also requires a reasonable explanation.
Identify the business’s own supplies
For trend ratios and turnover reconciliation, remove amounts that are included in return totals but are not the business’s own supplies: relevant supplies received under customer accounting, imported services and low-value goods subject to reverse charge in Box 14, remote services supplied for third parties by marketplaces in Box 15, and third-party low-value goods supplied through marketplaces or redeliverers in Box 16. Direct sales of the business’s own low-value goods remain its own supplies.
Step 2: select the review period
Choose the GST return with the highest combined total supplies and taxable purchases, using Boxes 4 and 5. A quarterly or six-month filer reviews that selected return. A monthly filer selects three consecutive monthly returns that include the highest-value month, and the sampling must cover all three months. Document the selection rather than choosing a quiet or convenient period.
General substantive sampling rules
For an applicable category with 30 or fewer transactions, test all transactions. Otherwise start with at least 30 samples covering at least 30% of the listing value, increasing the sample if needed to meet value coverage, up to 60 transactions. Standard-rated supplies have a 40-transaction cap instead. Cover material transaction types, months and group members rather than simply the largest invoices. These prescribed minimum methods apply when IRAS requests ASK; the guide also recommends them for voluntary reviews. The sample limits do not establish that untested transactions are correct.
Step 3A: standard-rated supplies and output tax
Reconcile standard-rated listings to Boxes 1 and 6 and the relevant customer-accounting, reverse-charge and overseas-vendor boxes. Check invoice completeness, credit notes and the time-of-supply rule, generally the earlier of invoice or payment. Include non-trading receipts, asset disposals, related-party supplies, local sales made as an overseas principal’s agent, expense recoveries and deemed supplies. Gifts costing over S$200 can require output tax where input tax was claimed, subject to the commercial-sample treatment. Ensure that debit and credit notes adjust the original transaction only once.
Rates, currency and customer accounting
Apply the tax rate appropriate to the transaction and report values in Singapore dollars. A foreign-currency tax invoice must show its GST amount in Singapore dollars; a simplified invoice may require extracting tax using the applicable fraction, such as 9/109 at a 9% rate. Relevant prescribed goods supplied to a GST-registered business customer for more than S$10,000 can fall under customer accounting: the supplier does not collect that GST and the customer accounts for output tax. Check eligibility, the customer-accounting invoice and corresponding credit notes, rather than applying the arrangement to every high-value sale.
Reverse-charge checks and minimum samples
Check at least 10 reverse-charge transactions, including at least three imported-services transactions and three low-value-goods transactions where those categories occur. Verify invoices or permitted alternative evidence, Singapore-dollar values, tax rates, output tax, input-tax entitlement and residual input-tax apportionment. Inter-branch and intra-group imports can still be relevant. Deductions for wages or interest must be supported where allowed; withholding tax does not reduce the reverse-charge value. Freight and insurance can form part of a low-value good’s value, and credit adjustments should follow the original transaction.
Overseas-vendor and platform supplies
The selected samples must include at least three transactions for each applicable category: remote services supplied through marketplaces, imported low-value goods supplied by marketplaces or redeliverers for third parties, and direct sales of imported low-value goods. Check Singapore customer status and the applicable business-to-consumer treatment, including any prior approval for special local or business-to-business arrangements. The GST registration status of the underlying low-value-goods supplier does not by itself remove a marketplace’s obligation to account for the deemed supply.
Low-value-goods pricing, refunds and double taxation
Include relevant freight and insurance in the taxable value. A discount borne wholly by the supplier or marketplace reduces the consideration, whereas a bank-funded or other reimbursed third-party discount generally does not: use the amount before that discount. Allocate shared freight fairly between low-value and other goods. For a refund of wrongly charged GST to a registered customer, keep the GST-registration evidence. If GST was charged both at sale and import, retain the customer’s import permit or postal tax receipt and evidence linking the sale and refund, rather than simply reversing tax without support.
Step 3B: zero-rated exports of goods
Reconcile the zero-rated listing to Box 2 and ensure transactions are neither exempt nor out of scope. Export zero-rating requires transaction evidence as well as transport evidence, even though ASK’s selected checks focus on transport documents. Depending on the mode and arrangement, evidence can include bills of lading, air waybills, export permits, consolidated or subsidiary export certificates, shipment notes or courier dispatch records. Documents should establish that the exported goods match the goods sold, including parties, descriptions and quantities. Changi hand-carried exports from 1 April 2009 use the endorsed HCES documentation; other departure points require the appropriate supporting arrangement.
International services are not automatically zero-rated
Check the particular section 21(3) category rather than assuming every overseas customer qualifies. The guide covers international transportation, specified services relating directly to land or goods outside Singapore or goods for export, performances wholly outside Singapore, qualifying services to overseas persons with the required location or GST-registration conditions for beneficiaries, prescribed business services and international telecommunications. Establish where the service is performed, where the customer belongs and who directly benefits. The fact that a customer pays from overseas is not sufficient.
Step 3C: exempt supplies and valuation
Businesses actively making exempt supplies, such as residential property, financial services, qualifying investment precious metals or digital payment tokens, should perform the substantive exempt-supply review and reconcile Box 3. Other businesses should still check incidental exempt supplies such as bank interest, foreign-exchange transactions and related-party loans, with attention to regulation 33 and non-regulation-33 supplies. Share disposals are reported using the gross sale value; relevant hedging gains or losses use the absolute realised net amount, not unrealised changes. Credit-note adjustments and the classification of each exempt transaction must be checked.
Step 3D: purchases and input-tax entitlement
Reconcile purchase and claim listings to Boxes 5, 7, 10 and 11. Use the ordinary purchase samples and add five samples for each applicable tourist refund, bad-debt relief and reverse-charge refund category. Check genuine business purpose, attribution to taxable supplies, a valid invoice or import document, correct period, the supplier’s GST registration and duplicate claims. The business cannot claim tax before obtaining the necessary document or use its own exchange rate instead of the Singapore-dollar GST amount or supplier’s rate on the invoice. Check credit notes and repay input tax on purchases unpaid for 12 months after their payment due date.
Blocked expenses and medical exceptions
Review expenses specifically excluded from input-tax recovery, including private motor cars, certain club fees, medical costs and insurance, and expenses for family members. Medical or accident-related expenses can have exceptions under the Work Injury Compensation Act or qualifying collective agreements. From 1 October 2021, qualifying medical treatment linked to the nature of work and health risks can be supported by written medical advice and relevant Singapore treatment requirements; qualifying COVID-19 measures can also be relevant. Do not treat all staff welfare expenditure as deductible merely because it was paid by the employer.
Tourist refunds, bad debts and reverse-charge refunds
For tourist refunds, verify the approved transaction data and electronically signed clearing-house records, the original output tax and the refund amount. Customs endorsement generally needs to be obtained within two months of the original invoice; the tourist must claim within two months of approval and the refund must be made within three months of approval. Historical cruise-terminal arrangements in the guide should not be mistaken for a current universal process. Bad-debt relief and reverse-charge refunds require their own eligibility checklists and supporting evidence, not just a journal entry reducing output tax.
Step 3E: suspended and deferred import tax
Reconcile suspended imports under MES and other relevant schemes to Boxes 9 and 5, and check Customs permits, agents’ records and internal listings for omissions, duplication or unauthorised scheme use. IGDS requires the relevant import value in Box 21, deferred GST in Box 19 and eligible purchase/input-tax amounts in Boxes 5 and 7. Use the applicable permit or approval period and include supplementary assessments where relevant. The guide notes the 2023 renumbering of deferred import GST from Box 17 to Box 19; old working papers must not direct amounts to the wrong box.
Ownership, importer identity and overseas principals
Import documents should identify the business correctly and support its business purpose. If goods are bought locally but imported by the buyer, ownership should have passed before import, supported by the relevant invoice and transaction evidence. Imports for overseas principals must meet section 33(2), 33A or 33B requirements as applicable, including correct principal identity and the subsequent local sale, re-export or value-added re-import treatment. A wrongly named importer needs genuine alternative evidence and preventive measures; it is not resolved simply by assuming the goods belonged to the business.
Trace the subsequent movement of imported goods
The guide’s flowchart separates own imports into trading goods, fixed assets, raw materials and section 33B re-imports. For this specific movement-tracing step, own trading goods require one sample with the highest import-permit value; fixed assets, raw materials and section 33B re-imports do not require the next tracing action in that flowchart. For goods imported for overseas principals, select the highest-value permit for each principal. Trace those selected goods to storage, local sale, export to a customer or return to the same overseas principal under section 33A, using warehouse and sales/export evidence. Other applicable eligibility checks remain necessary.
Limited inventory-process alternative
For the business’s own MES or IGDS goods without unique identifiers or involving numerous subsequent movements, the guide permits documented inventory processes and controls to replace the detailed tracing step. An ATA or ATP must perform the inventory walkthrough and test at least five transactions for each of inbound receipt, storage and outbound movement. This alternative does not apply to goods imported for others under sections 33(2), 33A or 33B. Where those goods cannot be traced, report the affected total import value rather than treating the inventory concession as a general exemption.
Step 4: reconcile financial turnover and supplies
Compare sales or turnover in the accounts with the year’s own GST supplies, using comparable periods and explaining legitimate differences in timing, valuation or out-of-scope transactions. Management accounts, audited adjustments or a reasonable allocation between financial years can be used where periods differ; a foreign business can use its Singapore management accounts rather than skip the comparison. If GST supplies are below accounting sales and standard-rated supplies are at least 75% of total supplies, reconcile a difference above S$150,000. If that ratio is below 75%, the threshold is S$500,000. Where GST supplies are not below sales, that particular ASK reconciliation action is not required, but other accuracy checks still apply.
Review non-trading and out-of-scope transactions
The turnover review should also identify related-party interest, reverse-charge expenses, fixed-asset disposals, commercial-property transactions and overdue purchase payments. Out-of-scope transactions still need purchase orders, delivery records, invoices, payment evidence, shipping documents or free-trade-zone warehouse records as appropriate. They can be tested indirectly when checking wrongly zero-rated supplies and when reconciling turnover; omission from a separate sample category does not remove the duty to support their treatment.
Step 5: quantify and correct errors
Classify findings as isolated or recurring and distinguish GST amount errors from other return-value errors. Isolated errors are quantified for the selected transaction or period as applicable; recurring GST errors require checking the selected period, the other periods in the review year and the preceding five years up to the current period. Rectify promptly, using consolidated annual GST F 7 disclosures where appropriate or the next F 5 only when the correction concession applies. Identify the cause and improve controls. A GST group’s pre-entry member errors need a separate disclosure, and recurring group errors can require quantification for former members over the five-year period.
Conditions for correcting errors in the next F 5
The guide’s FAQ permits next-return correction only where the combined net GST error across all affected periods is no more than S$3,000, measured as the additional Box 6 output tax less additional Box 7 input tax. In addition, the total errors in other boxes, excluding Boxes 6, 7 and 12, must be no more than 5% of Box 4 total supplies for each affected period. If a period had no supplies, use Box 5 taxable purchases for the 5% test. Otherwise submit the relevant F 7 disclosures. These are cumulative conditions rather than alternatives.
Declarations, working papers and scheme reassessment
Complete the ASK declaration even where no error is found; an error-disclosure template is unnecessary in a no-error case. Working papers normally need not accompany that declaration, but must be retained and provided if requested. If corrected figures affect a GST scheme condition, reassess qualification: for example, the guide refers to the MES zero-rated-supplies test of more than 50% of total supplies or more than S$10 million over 12 months. The declaration does not prevent IRAS from conducting further checks, and additional errors found by IRAS do not receive ASK voluntary-disclosure treatment merely because a review was undertaken.
What the certifying professional verifies
The ATA or ATP evaluates trend explanations, the selected return and whether applicable transaction categories were covered. Analytical work looks for missing or non-sequential invoices, mismatched tax calculations, standard-rated transactions with no GST, zero-rated or exempt codes with GST, duplicate purchases and disallowed input tax. For reverse-charge businesses, compare expenses with Box 14 to identify omitted imported services or low-value goods. Verify selected supplies for value, cut-off, classification and export matching; verify purchases for valid evidence, business purpose, taxable attribution, Singapore-dollar amounts, period and importer/consignee identity. Record exceptions and expand testing, including previously unselected transactions, where risk warrants.
Certification sample sizes for supplies
For ordinary standard-rated supplies, the certifier verifies 10 transactions per category if the business tested 30 or fewer, or 15 if it tested more than 30. Reverse-charge imported services and low-value goods require 10 per category. Each platform remote-services, third-party low-value-goods and direct low-value-goods category requires three. Zero-rated supplies require 10 per category where the business tested 30 or fewer, or 20 where it tested more than 30. Businesses actively making exempt supplies require 20 non-regulation-33 exempt transactions irrespective of their own sample size; this certification category is not applicable to general businesses. If fewer than a category’s minimum exist, certify all of them.
Certification sample sizes for purchases and claims
Certification requires 20 local taxable purchases and 10 transactions per applicable import category: GST paid, GST suspended and GST deferred. Tourist refunds, bad-debt relief and reverse-charge refunds each require five claims. These certification minimums apply regardless of the number used in the business’s annual review; where the available population is smaller, verify the whole population. Certification is an additional professional check, not a replacement for the business’s larger substantive samples or required extra testing.
Appendices: error register and certification evidence
Appendix 1 provides an error map covering return transcription and currency errors, trade and non-trade sales, property and asset sales, trade-ins as two supplies, agency transactions, customer accounting, reverse charge, platform supplies, failed export zero-rating, exempt valuation and input-tax restrictions. It also covers refunds, overdue payments, suspended/deferred imports and goods that cannot be traced. Appendix 2 records the entity, UEN, year, selected periods, preparer and sign-off; analytical procedures; sample counts; document dates and numbers; counterparties; values and GST; test outcomes; and numbered exceptions with revenue impact. Its supply and purchase test legends make the documentary basis of certification explicit.
Version history and related guidance
The guide’s amendment record explains major developments from 2014 to 2024: section 33B re-import rules, sampling changes, administrative concessions, customer accounting, reverse charge and overseas-vendor rules, digital payment tokens, SCTP accreditation terminology, medical-expense treatment, the 2023 low-value-goods expansion and return-box changes, the 2024 9% GST rate and S$3,000 correction threshold, and revised F 5 correction conditions from July 2024. Separate scheme guides, the Voluntary Disclosure Programme and the common-error concession materials remain important references for matters outside this guide’s detailed procedures.
Official source
This article independently explains the substantive contents of the official PDF, including the relevant conditions, procedures and annexes. The linked document remains the authoritative source for its original wording, and later changes should be checked separately.
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