What is a tax invoice (Singapore)?

A tax invoice is the document a GST-registered Singapore business issues when supplying standard-rated goods or services to a GST-registered customer. It's the legal basis on which your customer claims input tax, and IRAS sets specific format and timing rules.

When you must issue a tax invoice

You must issue a tax invoice within 30 days from the time of supply when:

You are GST-registered, and
Your customer is GST-registered, and
The supply is standard-rated (i.e. 9% applies).

You don't need to issue a tax invoice for zero-rated supplies, exempt supplies, deemed supplies, or sales to non-GST-registered customers (though you may still issue an ordinary commercial invoice).

Required fields on a tax invoice

IRAS requires every tax invoice to include:

The words "Tax Invoice" in a prominent place
Your invoice number (sequential and unique)
Your invoice date
Your name, address, and GST registration number
Your customer's name and address
A description of the goods or services
The quantity / extent of the supply
The amount payable excluding GST
The GST rate and the GST amount (shown separately, in SGD)
The total amount payable including GST, in SGD

If the supply spans multiple GST rates (e.g. standard + zero-rated lines), the rate must be shown against each line and the GST totals broken out.

Simplified tax invoice

If the total amount payable (including GST) does not exceed S$1,000, you may issue a simplified tax invoice. A simplified tax invoice only needs:

Your name, address, and GST registration number
The invoice date
A description of the goods or services
The total amount payable including GST
A statement that the price includes GST (e.g. "Price includes GST")

Common at retail point of sale where issuing a full tax invoice for every under-S$1,000 transaction would be impractical.

The InvoiceNow overlay

Under the GST InvoiceNow Requirement, the data on a tax invoice is also transmitted to IRAS via the Peppol network. The required fields above don't go away — they become the data points IRAS expects in the PINT-SG XML schema. Customer UEN, customer name, and customer address are mandatory submission fields.

If your invoicing tool is on InvoiceNow-Ready Solution Provider list, it already maps these for you.

Common mistakes

Missing the words "Tax Invoice" (an invoice is not the same as a tax invoice under IRAS rules)
GST shown in a foreign currency only — SGD must appear, even if the contract is priced in USD
GST registration number missing — your customer can't claim input tax without it
Issuing more than 30 days after time of supply, then claiming input tax in the wrong period

GST (Goods and Services Tax) — GST is Singapore's broad-based consumption tax — currently 9% — charged on most goods, services and imports.
Input tax vs output tax — Output tax is the GST you charge customers on sales.
GST F5 — GST F5 is the quarterly GST return every GST-registered business in Singapore files with IRAS.
InvoiceNow — InvoiceNow is Singapore's nationwide Peppol e-invoicing network.

Sources

Last reviewed 29 May 2026. Verify any thresholds or dates against the official source above before relying on them.