A business must register for GST when its taxable turnover exceeds S$1 million under either the retrospective or prospective test.
The retrospective test looks at turnover for the calendar year. The prospective test applies when the business can reasonably expect turnover to exceed S$1 million in the next 12 months.
Businesses below the threshold can apply voluntarily, but registration brings ongoing filing, invoicing and accounting duties. Check the commercial impact before applying.
When is GST registration compulsory?
| Test | When it applies | Application deadline | Effective date |
|---|---|---|---|
| Retrospective | Taxable turnover for 1 January to 31 December exceeded S$1 million. | Apply between 1 and 30 January of the following year. | 1 March of the following year. |
| Prospective | The business can reasonably expect taxable turnover to exceed S$1 million in the next 12 months. | Apply within 30 days from the forecast date. | For liabilities arising on or after 1 July 2025, 2 months from the forecast date. |
The prospective test needs a supportable forecast. Signed contracts, accepted quotations, confirmed purchase orders, fixed recurring invoices or an established upward sales trend can show that the threshold will be exceeded.
A business plan, sales target or market estimate by itself is not enough.
IRAS provides a GST Registration Calculator to help businesses assess their liability.
What counts as taxable turnover?
Taxable turnover includes standard-rated and zero-rated supplies made in Singapore.
It excludes:
- Exempt supplies
- Out-of-scope supplies
- The sale of capital assets such as machinery, equipment, office furniture or a business property
The calculation is based on turnover, not profit. A loss-making business can still cross the registration threshold.
Reverse charge and overseas vendor registration have separate rules. This guide covers the usual registration tests for local businesses.
Can a business avoid compulsory registration?
A business whose turnover exceeded S$1 million under the retrospective test may be able to rely on the exception where all of the following are true:
- The prospective test does not apply.
- The business is certain that taxable turnover for the next 12 months will not exceed S$1 million.
- The fall in turnover is caused by a specific circumstance, such as a large-scale downsizing.
- The business keeps documents that support the forecast.
A business whose taxable turnover is wholly or mainly from zero-rated supplies can also apply for exemption from registration.
Review the current conditions in IRAS’s GST registration liability guide before relying on an exception.
Should a business register voluntarily?
Voluntary registration can make sense where the business incurs significant GST on purchases, imports goods or expects to cross the S$1 million threshold soon.
It can be less attractive where customers cannot recover GST, suppliers do not charge much GST, or the business is not ready for regular GST reporting.
A voluntary registrant must remain registered for at least 2 years, use GIRO, meet the responsibilities of a GST-registered business and comply with the GST InvoiceNow requirement when it applies.
IRAS’s voluntary registration guide explains the qualifying conditions and trade-offs.
How do you apply for GST registration?
Apply through myTax Portal using the business’s Corppass access. Our Corppass guide explains how business access works.
- Confirm whether the application is compulsory or voluntary.
- Prepare the turnover evidence and supporting documents.
- Complete the online GST registration form.
- Submit GIRO if the application is voluntary.
- Respond promptly if IRAS asks for more information or a guarantee.
IRAS processes 60% of complete applications within 10 working days and the remaining applications within 30 days.
Do not charge GST merely because the application has been submitted. Start charging from the effective date stated in the registration notice.
How does InvoiceNow affect a new registration?
Businesses that apply for voluntary GST registration on or after 1 April 2026 must comply with the GST InvoiceNow requirement.
Businesses that apply for compulsory registration on or after 1 April 2028 will also be included, subject to the stated exclusions. Existing GST-registered businesses are being brought into the requirement in phases.
See our GST InvoiceNow transition guide for the rollout dates and accounting-system preparation.
What happens if registration is late?
IRAS can backdate the effective date. The business must then account for GST on past sales even if it did not charge customers at the time.
A late registrant may also face a fine of up to S$10,000 and a penalty equal to 10% of the GST due.
If the business has missed the deadline, submit the application and disclose the delay instead of waiting for IRAS to identify it.
Common questions
Is the S$1 million threshold based on revenue or profit?
It is based on taxable turnover, not profit.
Can a business register before reaching S$1 million?
Yes. It can apply voluntarily if it meets the qualifying conditions and accepts the ongoing obligations.
When should a newly registered business start charging GST?
Start charging GST from the effective date stated by IRAS, not from the application date.
How long must a voluntary registrant remain registered?
At least 2 years.
Need help assessing or applying?
Leftright Corporate can review the registration basis, prepare the application and help set up the accounting workflow needed after registration.
See our accounting and compliance services for more information.
