GST (Goods and Services Tax) is Singapore's version of VAT. For most small businesses the real question is simple: "Do I have to register?" For the majority of new SMEs, the answer is not yet — but there's a clear line, and crossing it without registering is expensive. Here's the plain-English version.
The one number that matters: S$1 million
The current GST rate is 9% (unchanged since 1 January 2024), and the compulsory registration threshold is S$1 million in taxable turnover. Below that, you generally don't have to register. At or above it, you must. Most home-based and early-stage businesses are comfortably under the line — but you should know exactly how the line is measured.
When registration becomes compulsory
There are two tests — you must register if you fail either one:
- The retrospective test (looking back): your taxable turnover was more than S$1 million in the past calendar year. For calendar year 2025, you must apply by 30 January 2026, with registration taking effect 1 March 2026.
- The prospective test (looking forward): you reasonably expect your taxable turnover to exceed S$1 million in the next 12 months (for example, you've just signed a large contract). You must apply within 30 days of forming that expectation.
"Taxable turnover" means your total sales of goods and services made in Singapore that would be subject to GST — not your profit.
Voluntary registration (below S$1M)
You can register even if you're under the threshold. Some businesses do this to claim back the GST they pay on their own purchases, or because larger clients prefer dealing with GST-registered suppliers.
The trade-offs: once registered, you must charge 9% GST on your sales (which can make you pricier to non-GST customers), file GST returns (usually quarterly), and stay registered for at least 2 years. For a small B2C business, voluntary registration often isn't worth the admin. For a B2B business with GST-registered clients and significant input costs, it can be.
The new bit: GST InvoiceNow (e-invoicing)
This is recent and easy to miss. Singapore is phasing in GST InvoiceNow — a requirement to transmit invoice data to IRAS through the national InvoiceNow e-invoicing network (built on the international Peppol standard).
For new registrants it's already arriving:
- Since 1 November 2025, newly incorporated companies registering voluntarily for GST must adopt InvoiceNow.
- From 1 April 2026, all new voluntary GST registrants must adopt it.
- It then extends in stages to new compulsory registrants and existing businesses, through to April 2031.
If you're registering now — especially voluntarily — factor in getting onto an InvoiceNow-ready accounting solution. Check the current scope on IRAS before you register.
How to register
Registration is done online via the IRAS myTax Portal, using your Corppass. If you're registering voluntarily, the person responsible for your GST matters generally needs to complete IRAS's e-Learning course first (and pass the quiz), unless exempted. Once approved, IRAS issues your GST registration number and effective date.
The penalty for registering late
This is why the threshold matters. If you cross S$1M and fail to register on time, IRAS back-dates your registration to when you should have registered — and charges GST on every sale you made in the interim. Because your customers are long gone, that GST comes out of your own margin, not theirs. Late registration can also trigger a penalty and a fine of up to S$10,000. Watching the threshold as you grow is far cheaper than fixing this after the fact.
The honest caveat
GST rules, thresholds, deadlines, and the InvoiceNow timeline change — the figures above are current as of the verified date below, but always confirm on IRAS before you register or budget around GST. This is a plain-English overview, not tax advice; for anything material, check with IRAS or a qualified tax professional.