Tax invoices in Singapore: what IRAS requires

Once your business is registered for GST in Singapore, sales to other GST-registered businesses need a tax invoice. It's the document that lets your customer claim back the GST you charged, so IRAS sets out exactly what it must contain.

The free Singapore invoice generator prints all of it, and switches to a plain invoice when you're not registered.

What a tax invoice must show

1. The words "Tax Invoice", prominently.
2. An identifying number, in sequence.
3. The date of issue.
4. Your name, address and GST registration number — usually your UEN, sometimes an M-series number from IRAS.
5. Your customer's name and address.
6. A description of the goods or services, enough to identify them, and the type of supply.
7. For each item, the quantity of goods or extent of services, and the amount excluding GST.
8. Any cash discount you offer.
9. The total amount excluding GST, the GST rate (9%) and the total GST, as a separate amount.
10. The total amount payable including GST.
11. Where the invoice mixes kinds of supply, the zero-rated, exempt or other supplies shown separately with their amounts.

When to issue it

Issue a tax invoice within 30 days of the time of supply — usually when you deliver, perform the service, or receive payment, whichever is first. Your customer needs it to claim the GST in the right return.

A worked example

Say you're Merlion Studio Pte. Ltd., registered for GST, and you redesign a website for a dental practice in Raffles Place for S$4,000, plus S$200 of something exempt. Your tax invoice shows:

• Tax Invoice, INV-0042, dated 1 October 2026;
• Merlion Studio Pte. Ltd., 10 Anson Road #12-01, Singapore 079903, GST Reg. No. 201828446N and the UEN;
• Tanjong Dental Pte. Ltd. and their address;
• the website redesign at S$4,000 with GST at 9%, and the exempt item at S$200, shown separately;
• total excluding GST S$4,200, GST at 9% S$360, total including GST S$4,560.

Add PayNow and the invoice carries a QR code with the amount and invoice number, so your customer pays in a few taps.

Simplified tax invoices

When the total including GST is S$1,000 or less, you may issue a simplified tax invoice instead: your name, address and GST number, the date and number, a description, the total including GST and the words "Price payable includes GST". It doesn't need your customer's details. Since a full tax invoice is valid at any amount, many businesses just use the full form every time.

Invoices in other currencies

You can bill a Singapore customer in US dollars or another currency, but a tax invoice then also shows, in Singapore dollars, the total excluding GST, the GST and the total including GST, converted at an exchange rate IRAS accepts. Invoice Native prints the exchange rate and the three S$ amounts under the totals.

Credit notes

To reduce a tax invoice — a refund, a discount agreed later, a mistake — issue a credit note. It shows its own number and date, both businesses' details, the original invoice's number, the reason, and the amount and GST credited. If you and your customer agree not to adjust the GST, mark the credit note "This is not a credit note for GST purposes"; it then credits only the price.

Common mistakes

• Calling it a tax invoice before you're registered. Only GST-registered businesses may issue tax invoices or charge GST.
• Leaving out your GST registration number. Your customer can't claim the GST without it.
• One total for mixed supplies. Show zero-rated and exempt items separately from standard-rated ones.
• Zero-rating because the address is abroad. International services are only zero-rated when they qualify under section 21(3) — see zero-rating international services.

Customer accounting for prescribed goods

When a GST-registered business sells mobile phones, memory cards or off-the-shelf software to another GST-registered business, and those prescribed goods come to more than S$10,000 on the invoice excluding GST, the customer accounts for their GST instead of the supplier. The tax invoice then shows the GST the customer must pay and the statement "Customer accounting: customer to pay GST of S$X to IRAS". Invoice Native has a supply type for this; mark the prescribed goods on their lines.

Keeping records

IRAS requires you to keep business records, including copies of the tax invoices and credit notes you issue, for 5 years. Signed-in Invoice Native businesses keep every issued document, numbered and unchangeable once issued, and see a GST F5 summary for each period.