GST Record Keeping in Singapore: Tax Invoices, Input Tax and Export Evidence

What GST records should a Singapore business keep?

A GST-registered business should keep records that explain both sides of the GST return. For output tax, the business needs evidence of sales, tax invoices, credit notes, standard-rated supplies, zero-rated supplies, exempt supplies and any adjustments. For input tax, it needs supplier tax invoices, import permits and evidence that the purchases are used for business purposes.

The GST F5 return is only the final declaration. The records behind it should show how each figure was built. If the business cannot reconcile the GST control account to the GST F5 return, the problem should be fixed before the return is filed, not after IRAS asks questions.

Common mistakes include claiming GST from receipts that are not tax invoices, claiming GST on invoices addressed to a director or related company, treating all overseas customer sales as zero-rated without export support, forgetting to adjust GST after credit notes, and not reconciling the GST control account after filing. These issues may not be obvious from the profit and loss statement, which is why a GST-specific review is needed before submission.

What to keep for each GST F5 return

Common GST record keeping mistakes

This is especially important for SMEs with e-commerce sales, multiple payment channels, imports or cross-border services. Platform payouts may combine sales, refunds, commission, advertising fees, shipping charges and withholding adjustments. The GST treatment should be based on the underlying supply and supporting documents, not merely on the net cash received.

For each GST period, keep a compact GST review file rather than a pile of disconnected invoices. The file should contain the submitted GST F5 return, the output tax listing, the input tax listing, the GST control account reconciliation, the list of excluded or blocked input tax items, and notes for unusual transactions. If a number in the GST F5 cannot be traced to a listing or schedule, the return is not review-ready.

Tax invoices and credit notes are the GST backbone

IRAS describes a tax invoice as the main document supporting an input tax claim. For customers, the sales tax invoice also explains why GST was charged and when the supply was made. A GST-registered company should therefore use a consistent invoice format and avoid manual edits that are not reflected in the accounting system.

Credit notes should not be treated as informal discounts. If goods are returned, a price reduction is given or an invoice is cancelled, the GST treatment should be properly documented. The credit note should connect to the original invoice and the GST adjustment should be picked up in the correct GST return period.

Input tax claims need more than payment evidence

A common SME mistake is to claim input tax because the company paid for something. Payment alone is not enough. The purchase should satisfy IRAS input tax conditions, including that the business is GST-registered, the goods or services are supplied to or imported by the business, and they are used or will be used for business purposes.

Practical issues usually arise with director expenses, staff reimbursements, overseas invoices, mixed personal and business purchases, entertainment, blocked claims, and invoices addressed to a related party. These items should be reviewed before the GST F5 is filed.

Zero-rated exports need export evidence

Charging GST at 0% is attractive, but zero-rating is not automatic just because a customer is overseas. For exported goods, the business should be certain that the goods will be exported or have been exported, and it should hold the required documents to support zero-rating.

Export evidence may include export permits, shipping documents, freight documents, commercial invoices, delivery orders, bills of lading, airway bills or other transport evidence. The exact documents depend on the shipping arrangement. Where marketplace or logistics platforms are involved, the company should download and retain the evidence before it disappears from the portal.

A monthly GST record keeping workflow

InvoiceNow and digital readiness

IRAS has introduced GST InvoiceNow requirements in phases for GST-registered businesses. Even before a business is in scope, it is sensible to improve invoice data quality: customer names, UENs, GST registration details, tax codes, invoice dates and credit-note links should be clean enough for digital reporting.

Good GST record keeping therefore supports more than historical compliance. It also reduces future enquiry pain when invoice data needs to be transmitted or reviewed in a more structured format.