Invoice generator for Singapore: a free invoice and GST tax invoice template

What must a Singapore invoice include?

That depends on whether you are GST-registered. A business that is not registered issues a plain invoice with no GST. A registered business must give GST-registered customers a tax invoice carrying the twelve particulars IRAS lists, or a simplified tax invoice when the total including GST is S$1,000 or less.

IRAS's invoicing rules are written for GST-registered businesses. Without GST, a company must still show its name and registration number on its invoices under section 144 of the Companies Act 1967, and the same basics (number, date, customer, description, total) are what any customer's accounts team expects.

A worked example

Press Try an example above. A GST-registered studio bills website design at S$2,400, twelve months of hosting at S$25 and a logo at S$800 less 10%. The lines come to S$3,420.00 before GST, the GST at 9% is S$307.80 and the total is S$3,727.80. Every particular on the checklist shows Done. Change Type to Simplified and the checklist warns that the total is over S$1,000, so a full tax invoice is needed.

What is the difference between a tax invoice, an invoice and a receipt?

A tax invoice is the GST-registered supplier's bill that lets a GST-registered customer claim the GST back as input tax. An invoice is any other bill. A receipt is proof of payment.

• Tax invoice: required when a registered business makes a standard-rated supply to a GST-registered customer. It is not required for zero-rated or exempt supplies; if you issue one for a zero-rated supply, show GST at 0%.
• Invoice: what a business that is not GST-registered issues, with no GST on it. IRAS says only GST-registered businesses can charge GST, and a tax invoice must carry a GST registration number, so an unregistered business has no basis to call its bill a tax invoice. This generator titles it "Invoice" and shows no GST.
• Receipt: a registered business may issue one instead of a tax invoice to a customer who is not GST-registered. It must be serially printed and show the date, the business name and GST registration number, the total including GST and the words "Price payable includes GST". You must still issue one if a customer asks.

When must you issue a tax invoice?

Within 30 days of the time of supply, whenever the customer is GST-registered. The time of supply is normally the earlier of the date you issue an invoice and the date you are paid (IRAS time of supply rules), and it decides which GST return the sale goes into. Sales orders, pro-forma invoices and statements of account are generally not treated as invoices for GST purposes, so sending one does not trigger the time of supply. No tax invoice is needed for zero-rated, exempt or deemed supplies, or for customers who are not GST-registered.

How should you number invoices?

Give every invoice a unique number: IRAS's list asks for "an invoice identifying number" and sets no format, so prefixes, years and separate series for different branches are all fine as long as no number repeats. A single unbroken sequence such as INV-2026-001, INV-2026-002 makes gaps and duplicates easy to spot. The Next number button continues your sequence and keeps its zero padding, and with Save on this device ticked it remembers the last number you downloaded.

Never reuse a number or quietly edit an invoice you have issued. IRAS expects a mistake or a later discount to be corrected with a credit note that states its own number and date, the reason for the credit and the number and date of the original tax invoice.

How do you invoice in a foreign currency?

You may bill in US dollars or any other currency, but a tax invoice must also show three figures in Singapore dollars: the total excluding GST, the total GST and the total including GST. Your customer can claim input tax only on the amounts you state. Choose a currency above and enter the exchange rate, and the generator adds that block.

The rate must be acceptable to IRAS. Its e-Tax guide on exchange rates (fourth edition, 30 January 2026) accepts rates from sources such as MAS and local banks, provided the rate reflects the Singapore market at the time of supply, is updated at least every three months and is used consistently for at least a year.

How is GST rounded on an invoice?

Work out 9% on each standard-rated line and add the results, or apply 9% once to the subtotal; IRAS accepts either if you are consistent, and the two can differ by a cent. Round the total GST to the nearest cent. When your prices include GST, the GST is 9/109 of the standard-rated total. Our Singapore GST calculator shows both methods side by side, and the Round the GST switch above applies either one to the whole invoice.

How long must you keep invoices?

At least five years (IRAS: keeping records), even if you stop trading or deregister (IRAS: responsibilities of a GST-registered business). That covers the tax invoices you issue and the ones you receive.

GST-registered businesses are also moving to InvoiceNow, Singapore's e-invoicing network, and must send invoice data to IRAS through an InvoiceNow-Ready Solution. Businesses that apply to register voluntarily on or after 1 April 2026 are already in; existing registrants join in phases from 1 April 2028 to 1 April 2031 by size (IRAS GST InvoiceNow Requirement). A PDF from this page sends nothing to IRAS, so once your phase starts, issue tax invoices from an InvoiceNow-Ready Solution.

Common invoicing mistakes

• Adding GST, or the words "Tax Invoice", before your GST registration takes effect.
• Using a simplified tax invoice for a total over S$1,000 including GST.
• Leaving out the customer's address or your GST registration number on a full tax invoice.
• Showing only foreign-currency totals on a tax invoice.
• Charging 9% on zero-rated or exempt lines.
• Issuing a tax invoice more than 30 days after the time of supply.
• Editing or deleting an issued invoice instead of issuing a credit note.

How Olano helps

Olano Studio builds AI agents for Singapore businesses' admin and customer work, such as an operations agent that triages the shared inbox, drafts replies and chases follow-ups, with anything outbound waiting for your approval (AI inbox assistant). If your books are in QuickBooks Online, an agent can draft invoices, send them and record payments in the connected company, (Olano user guide), and it can be set to ask a person before it creates or sends anything. It works alongside your accountant, not instead of one. We quote every engagement as a fixed proposal in Singapore dollars, exclusive of GST: see our services or discuss a project.