Goods and Services Tax (GST) is Singapore’s broad-based consumption tax levied at 9% on the supply of goods and services in Singapore. For business owners, GST registration is not optional once you cross the turnover threshold — and the consequences of late registration can be severe. This guide explains exactly when you must register, how to register, what voluntary registration means, the new InvoiceNow requirements, and how to manage your ongoing GST obligations.
The GST Registration Threshold: When Must You Register?
Under the Goods and Services Tax Act 1993, a business must register for GST under either the retrospective basis or the prospective basis:
Retrospective Basis
At the end of any calendar year (31 December), if your taxable turnover for the past 12 months has exceeded S$1 million, you must register for GST. You must apply within 30 days of the end of that calendar year — i.e., by 30 January of the following year. GST registration will be effective from 1 March of that year.
Prospective Basis
At any point during the year, if you have reasonable grounds to expect that your taxable turnover in the next 12 months will exceed S$1 million, you must register within 30 days of forming that belief. Registration is effective from the date you are required to be registered, not the date you apply.
| Basis | Trigger | Application Deadline | Effective Date |
|---|---|---|---|
| Retrospective | Taxable turnover > S$1M in past 12 months (measured at 31 Dec) | 30 January | 1 March |
| Prospective | Reasonable expectation of > S$1M in next 12 months | Within 30 days of forming belief | Date required to register |
What Counts as Taxable Turnover?
Taxable turnover includes the total value of standard-rated supplies (taxed at 9%) and zero-rated supplies (taxed at 0%, such as exports and international services). It does not include exempt supplies (such as financial services and residential property rental), out-of-scope supplies, and the sale of capital assets used in the business.
This distinction matters. A company providing primarily exempt services — such as a licensed moneylender or a property investment holding company receiving only residential rental income — may never reach the GST registration threshold regardless of revenue, because exempt supplies are excluded from taxable turnover.
Consequences of Late GST Registration
This is where many business owners get caught out. If IRAS determines that you should have been GST-registered from an earlier date, it will backdate your registration and require you to account for GST on all taxable supplies made since that date — even if you did not collect GST from your customers. You will have to pay GST out of your own pocket, plus late registration penalties of up to S$10,000 and potential prosecution.
The moral: monitor your turnover regularly — at least quarterly — and do not wait until the end of the year to assess your registration obligation.
Voluntary GST Registration: Should You Register Early?
Businesses below the S$1 million threshold may register for GST voluntarily. IRAS may approve voluntary registration where the business makes or intends to make taxable supplies. Voluntary registration is attractive in certain situations:
When Voluntary Registration Makes Sense
- Your customers are GST-registered businesses — they can claim back the GST you charge them, so your pricing is not impacted
- You incur significant GST on purchases — by registering, you can recover input tax on rent, equipment, professional services, and other business expenses, improving cash flow
- You are approaching the threshold — registering early avoids the risk of late registration and gives you time to set up proper systems
When Voluntary Registration May Not Make Sense
- Your customers are end consumers — GST registration means charging customers 9% more, which may reduce competitiveness if rivals are not GST-registered
- Your business has low GST-bearing inputs — if you do not incur much GST on purchases, there is less input tax to recover
- Administrative burden outweighs benefit — voluntary registrants must remain registered for at least two years and comply with all GST filing and record-keeping obligations
The InvoiceNow Requirement: What You Need to Know for 2026
IRAS is progressively rolling out a requirement for GST-registered businesses to use InvoiceNow-ready accounting software to transmit invoice data electronically to IRAS. The rollout timeline is:
| Category | Mandatory InvoiceNow Date |
|---|---|
| New voluntary GST registrants | From 1 November 2025 |
| All new compulsory GST registrants | From 1 April 2026 |
| Existing GST-registered businesses (large) | To be announced (phased rollout) |
If you are registering for GST from April 2026 onwards — whether compulsory or voluntary — you must use accounting software that supports InvoiceNow (based on the Peppol e-invoicing network). Businesses that do not comply may face penalties. Check the IRAS website for the current list of approved InvoiceNow-ready software vendors.
How to Register for GST
GST registration is done online via the IRAS myTax Portal using your company’s CorpPass login. The process involves:
- Log in to myTax Portal with CorpPass
- Select “GST” → “Apply for GST Registration”
- Complete the online application form, providing details of your business activities, estimated turnover, and date of liability
- For voluntary registration: upload a business profile, financial statements or bank statements, and evidence of business activity
- Submit the application — IRAS typically processes mandatory registrations within 3 working days and voluntary registrations within 10 working days
Your Ongoing GST Obligations After Registration
Once registered, your key obligations are:
| Obligation | Detail |
|---|---|
| Charge GST on taxable supplies | 9% on standard-rated supplies; 0% on zero-rated supplies; no GST on exempt supplies |
| Issue tax invoices | Within 30 days of making a taxable supply; must include GST registration number and GST amount |
| File quarterly GST returns (Form F5) | Within 1 month of the end of each accounting period |
| Maintain GST records | For at least 5 years |
| Pay net GST to IRAS | Together with the quarterly return filing |
| Notify IRAS of changes | Within 30 days of any material change to business activities, address, or contact details |
GST Deregistration: When Can You Cancel?
A business must cancel GST registration if it ceases to make taxable supplies, or if its taxable turnover is expected to fall below S$1 million for the next 12 months. Voluntary registrants cannot deregister until they have been registered for at least two years. Deregistration involves a final GST return and a “deemed supply” on business assets on hand at the date of deregistration.
For the full compliance picture, refer to our Singapore company compliance calendar which includes all GST filing deadlines alongside ACRA, IRAS income tax, and CPF obligations. You may also find our overview of Singapore corporate tax 2026 a useful companion guide.
How Raffles Corporate Services Can Help
Raffles Corporate Services provides GST registration assistance, quarterly GST return preparation, and GST compliance advisory for Singapore companies. Whether you have just crossed the S$1 million threshold or are considering voluntary registration, we can advise on the right approach and manage your GST filings on an ongoing basis.
Contact us today to discuss your GST registration or compliance requirements.
— The Editorial Team, Raffles Corporate Services