- GST registration becomes compulsory once your taxable turnover passes S$1 million, tested on both the past calendar year and the next 12 months. You have 30 days to apply once you are liable.
- Any business registering voluntarily must now transmit invoice data to IRAS through InvoiceNow, the rule having reached all new voluntary registrants on 1 April 2026.
- Registering late means backdated GST on past sales, a fine of up to S$10,000 and a 10% penalty, so monitoring turnover early costs far less than fixing it afterwards.
Getting GST registration in Singapore right is a matter of timing, not paperwork. Cross S$1 million in taxable turnover and IRAS expects you to act within 30 days, whether or not you noticed the line approaching.
The trouble is that most owners only ask the question after a big contract lands or a year-end tally surprises them. By then the clock is already running, and the cost of registering late comes straight out of your own pocket.
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The short answer You must register for GST in Singapore once your taxable turnover passes S$1 million, tested either over the past calendar year (the retrospective basis) or over the next 12 months (the prospective basis). You then have 30 days from becoming liable to apply. Businesses under the threshold can register voluntarily to recover the GST they pay on expenses, and any business that registers voluntarily today must transmit its invoice data to IRAS through InvoiceNow, Singapore’s national e-invoicing network. |
When must you register for GST in Singapore?
Registration is compulsory the moment your taxable turnover exceeds S$1 million. IRAS applies two separate tests, and you only need to fail one of them to become liable.
The retrospective test looks back. At the end of each calendar year (1 January to 31 December), you add up your taxable turnover, and if it crossed S$1 million, you apply by 30 January, with registration taking effect on 1 March.
The prospective test looks forward. If at any point you can reasonably expect your turnover to top S$1 million over the next 12 months, often after signing a major contract, you must apply within 30 days of that forecast.
The effective date differs between the two. For prospective forecasts made on or after 1 July 2025, registration now takes effect two months from your forecast date, an extension of the older rule that started GST on the 31st day. The 30-day window to apply has not changed.
|
Basis |
When you become liable |
Apply within |
Registration takes effect |
|---|---|---|---|
|
Retrospective |
Taxable turnover exceeded S$1 million at the end of the calendar year (31 December) |
30 days (by 30 January) |
1 March of the next year |
|
Prospective (forecast on or after 1 Jul 2025) |
You reasonably expect to exceed S$1 million in the next 12 months |
30 days of the forecast date |
2 months from the forecast date |
|
Prospective (forecast before 1 Jul 2025) |
Same forecast trigger |
30 days of the forecast date |
31st day after the forecast date |
Must register, should register, or can wait?
|
Your situation |
What to do |
|---|---|
|
Taxable turnover already over S$1 million in the past calendar year, or you forecast crossing it in the next 12 months |
You must register. Apply within 30 days of becoming liable. |
|
Under S$1 million, but you pay a lot of GST on rent, software or services, or your B2B clients prefer registered suppliers |
You should consider registering voluntarily. |
|
Under S$1 million, mostly selling to consumers, with little GST on costs and no near-term forecast above the threshold |
You can wait, but keep monitoring your turnover. |
What counts toward the S$1 million GST registration threshold?
The threshold is based on taxable turnover, not gross sales, so the figure you watch is narrower than your total revenue. Standard-rated supplies (charged at the 9% GST rate) and zero-rated supplies such as exports and international services both count toward it.
What does not count is just as important. GST-exempt supplies like most financial services and residential property, along with out-of-scope sales such as goods shipped entirely outside Singapore, sit outside the calculation, as do one-off sales of capital assets.
Two points trip people up. You cannot split one business into several to stay under the line, since IRAS will aggregate the turnover, and a zero-rated-only business can apply for exemption from registration rather than register and file nil returns.
Track your taxable turnover monthly, not just at year-end. Because the prospective test runs on a rolling 12-month view, a single large contract can make you liable well before the calendar year closes.
Should you register for GST voluntarily?
Plenty of businesses register before they have to. Voluntary registration lets you recover the GST you pay on costs like rent, software and professional services, which can be worth real money if your inputs are heavy.
It can also help you win work. Some corporate and agency clients prefer GST-registered suppliers, and registering early avoids a scramble if you are growing fast toward the threshold anyway.
There is a commitment to weigh, though. Once you register voluntarily, you must stay registered for at least two years and take on filing from day one. For the full decision, including when it works against you, see our guide to voluntary GST registration.
How do you register for GST in Singapore, step by step?
Registration runs through the IRAS myTax Portal and is free to submit. The steps are straightforward once you know which basis applies to you.
- Confirm your eligibility and which basis you are registering under, whether compulsory or voluntary.
- If you are registering voluntarily, complete the IRAS “Overview of GST” e-Learning course and keep the certificate for your application.
- Get InvoiceNow-ready if you are a voluntary registrant. You will need a Peppol ID from an accredited solution provider, which is a precondition before you apply.
- Prepare your documents: company UEN, a description of your business activities, financial statements or projected turnover, directors’ details, your financial year-end and your business structure.
- Submit the application through myTax Portal using Corppass and upload your documents. You can save and return to it.
- Wait for approval, typically 10 to 30 working days. IRAS issues your effective date and GST registration number, which must then appear on all your tax invoices.
Once you are registered, the work shifts to staying compliant. Our GST compliance checklist walks through charging GST, record-keeping and the quarterly filing cycle.
What is InvoiceNow and do you need it for GST registration?
InvoiceNow is Singapore’s national e-invoicing network, built on the international Peppol standard. It lets businesses transmit structured invoice data directly to IRAS rather than relying on paper or PDF invoices.
For new registrants, it is no longer optional. Since 1 November 2025, newly incorporated companies registering voluntarily have had to use it, and since 1 April 2026 the requirement covers all new voluntary registrants regardless of when they were incorporated. In practice, if you register voluntarily today, InvoiceNow is part of the deal.
The net is widening. Compulsory registrants are phased in from 1 April 2028, with all remaining GST-registered businesses due to be onboarded by April 2031. Overseas vendors under the OVR regime and businesses registered solely for reverse charge are excluded.
Getting ready is a short setup: choose an IMDA-accredited InvoiceNow-Ready solution (many common accounting platforms already qualify), register for a Peppol ID, and switch on the GST submission feature.
What does GST registration cost, and what happens if you register late?
Registering with IRAS itself carries no fee. The real cost is operational: making sure your invoicing software is InvoiceNow-ready and keeping up with quarterly returns once you are in the system.
Late registration is where it gets expensive. If you miss your window, IRAS can backdate your registration to the date you ought to have registered and make you account for the consequences below.
- Your registration is backdated to the date you should have registered.
- You must pay 9% GST on those past sales, even if you never collected it from customers.
- You face a fine of up to S$10,000.
- A penalty equal to 10% of the GST due is added.
- Prosecution is possible in serious cases.
There is some relief. If you come forward and voluntarily disclose that you registered late, IRAS generally waives the fine and the penalty, though the backdated GST itself still has to be paid, sometimes by instalment. For the ongoing picture once you are registered, see our guide to filing your GST returns, and if you want to sanity-check your wider tax position, the corporate tax calculator gives a quick estimate.
How Sleek helps you register for GST and stay compliant
The hard part of GST is not the form; it is knowing when you have crossed the line and keeping up afterwards. Sleek’s accounting services monitor your turnover against both tests, handle the myTax Portal application and your InvoiceNow setup, and file your quarterly returns so a deadline never catches you off guard.
Plans start from S$75 a month, with GST quarterly filing available from S$300 a year, so registration and filing are looked after from one place.
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FAQs about GST registration Singapore
When is GST registration compulsory in Singapore?
Registration is compulsory once your taxable turnover exceeds S$1 million, and you only need to meet one of two tests. The retrospective test is assessed every 31 December against the calendar year just ended, while the prospective test applies the moment you can reasonably forecast crossing S$1 million in the coming 12 months.
Can I register for GST if my revenue is under S$1 million?
Yes. You can register voluntarily at any time, but it comes with two conditions: you must stay registered for at least two years, and you must actually make taxable supplies within two years of registering or IRAS may cancel the registration.
What happens if I register for GST late?
IRAS backdates your registration, so you must account for 9% GST on past sales even if you never charged customers, and you can face a fine of up to S$10,000 plus a penalty of 10% of the GST due. If you voluntarily disclose the late registration, the fine and penalty are usually waived, although the backdated GST remains payable and can sometimes be paid in instalments.
Do I need InvoiceNow to register for GST?
If you register voluntarily, yes. All new voluntary registrants have had to transmit invoice data through InvoiceNow since 1 April 2026, and newly incorporated voluntary registrants since 1 November 2025. Compulsory registrants are brought in from 1 April 2028, while overseas vendors under the OVR regime and reverse-charge-only registrants are excluded.
What counts as taxable turnover for the S$1 million threshold?
Standard-rated supplies at 9% and zero-rated supplies at 0%, such as exports and international services, both count, but exempt supplies like financial services and out-of-scope sales do not. One-off capital asset sales are excluded too, and you cannot split a business into smaller entities to stay under the line, because IRAS will aggregate the turnover.
