In Singapore, “invoice” and “tax invoice” are not interchangeable — the label carries legal meaning. Using the right one keeps your GST-registered clients happy (they need it to claim input tax) and keeps you aligned with IRAS expectations.
When is a plain invoice enough?
If your business is not GST-registered, every bill you send is simply an “Invoice”. You don’t charge GST, you don’t show a GST line, and you must not call the document a Tax Invoice. This covers the majority of freelancers and small businesses under the S$1 million registration threshold.
When must you issue a Tax Invoice?
If you are GST-registered and you make a standard-rated supply to another GST-registered business, you must issue a tax invoice — it’s the document your customer uses to support their input tax claim. Generally it should be issued within 30 days of the supply.
What must a Singapore tax invoice show?
The words “Tax Invoice” prominently; your business name, address and GST registration number; an identifying invoice number and date; your customer’s name and address; a description of the goods or services; the amount payable excluding GST; the GST rate (9%) and GST amount shown separately; and the total including GST. If you also show your UEN, even better — many clients’ systems ask for it.
For small transactions there’s a lighter option: a simplified tax invoice is acceptable when the total including GST is S$1,000 or less. It can omit the customer’s details and just show the GST-inclusive total with a statement like “Price payable includes GST”.
Common mistakes that cause problems
Charging GST without being registered (an offence — don’t do it); labelling a document “Tax Invoice” when you’re not registered; showing a GST-inclusive lump sum without the separate GST amount on a full tax invoice; and rounding the GST line differently from the stated rate. A generator that handles the wording and math removes all four risks.
Skip the formatting worry: the Invoice Generator has a Singapore preset that produces the correct “Tax Invoice” layout — UEN, 9% GST calculated and shown separately, plus a PayNow QR so the invoice collects its own payment. Free to use; your data stays in your browser.
This article is general information, not tax advice — for edge cases, IRAS’s e-Tax guides are the authority.
Frequently Asked Questions
Can I issue a tax invoice if I’m not GST-registered?
No. Only GST-registered businesses may issue tax invoices or charge GST. If you’re not registered, issue a normal invoice with no GST line.
What is a simplified tax invoice?
A reduced-detail tax invoice allowed when the GST-inclusive total is S$1,000 or less. It still needs your name, GST number, date, description and the GST-inclusive amount, but can omit customer details.
Does the 9% GST rate apply to everything?
9% is the standard rate in 2026. Some supplies are zero-rated (e.g. exports, international services) or exempt — if that’s your situation, check IRAS guidance or an accountant before invoicing.