Goods and Services Tax (GST) registration in Singapore is mandatory once your business crosses the S$1 million taxable turnover threshold — but the obligations around it are more nuanced than many business owners realise. With new InvoiceNow requirements introduced in 2025 and 2026, and enhanced IRAS enforcement, this is the right time for every Singapore business to review its GST position.

This guide covers who must register, the two triggers for mandatory registration, how voluntary registration works, the 2026 InvoiceNow requirements, and the step-by-step process for registering with IRAS.

What Is GST and the Current Rate?

GST is a broad-based consumption tax levied on the supply of goods and services in Singapore and on the importation of goods. The current GST rate is 9%, which has been in effect since 1 January 2024 (increased from 8% in 2023 and from 7% in January 2023).

GST-registered businesses collect GST from their customers (output tax) and can claim back the GST they paid on business purchases (input tax). The net difference is paid to or refunded by IRAS.

When Must You Register for GST?

Under the Goods and Services Tax Act, there are two triggers for mandatory GST registration:

Trigger 1: Retrospective Turnover Test

You must register for GST if your taxable turnover for the past 12 calendar months has exceeded S$1 million. The 12-month lookback is assessed on a rolling basis — it is not based on your financial year. You must apply for GST registration within 30 days of the end of the calendar month in which you crossed the S$1 million mark.

Example: If your cumulative taxable turnover from June 2025 to May 2026 exceeded S$1 million, you must apply by 30 June 2026, and your GST registration will take effect from 1 August 2026.

Trigger 2: Prospective Turnover Test

You must also register if at any point you have reasonable grounds to believe your taxable turnover will exceed S$1 million in the next 12 months. This trigger is based on future expectations — a large signed contract, a confirmed order, or a business plan projecting revenues above S$1 million.

You must apply within 30 days of forming that belief. IRAS will take into account objective factors such as confirmed orders and signed agreements.

What Counts as Taxable Turnover?

Taxable turnover includes the value of standard-rated supplies (9% GST) and zero-rated supplies (0% GST), but excludes exempt supplies (e.g., financial services, sale of residential property) and out-of-scope supplies. If your business is primarily in an exempt supply sector, your GST registration obligations may differ. Review the IRAS GST registration guidance for your specific sector.

Consequences of Late Registration

Failing to register for GST on time is a serious compliance breach. IRAS may:

  • Backdate your GST registration to the date you should have registered
  • Assess GST on all taxable supplies made since the effective registration date — even though you did not collect GST from your customers during that period, meaning you bear the cost personally
  • Impose penalties for late registration — currently up to S$10,000 and/or up to two years’ imprisonment for wilful failure to register

In practice, late registrants often face a painful backpay position where they owe IRAS 9% of past revenues they never collected from customers. This is entirely avoidable by monitoring turnover proactively.

Voluntary GST Registration

Businesses with turnover below S$1 million may register for GST voluntarily. The primary benefit is the ability to claim input tax credits on business purchases — effectively recovering 9% of your qualifying business expenses from IRAS.

Voluntary registration is typically beneficial for:

  • Businesses making significant capital expenditure or purchases from GST-registered suppliers
  • Businesses whose customers are primarily GST-registered entities (who can reclaim the GST you charge)
  • Start-ups in their build-up phase with high input costs and low initial revenue

Voluntary registrants must remain registered for a minimum of two years. They also face additional obligations (see InvoiceNow below).

The 2026 InvoiceNow Requirement

A significant new obligation for GST-registered businesses took effect in phases from 2025:

  • From 1 November 2025: Newly incorporated companies that voluntarily register for GST must comply with the GST InvoiceNow requirement
  • From 1 April 2026: ALL new voluntary GST registrants must submit invoice data to IRAS via the InvoiceNow network, regardless of their incorporation date

InvoiceNow is Singapore’s national e-invoicing network, built on the Peppol framework. Compliance requires your accounting or invoicing software to be InvoiceNow-ready and capable of transmitting invoice data to IRAS through an IMDA-accredited Access Point Provider.

IRAS is extending this requirement to all GST-registered businesses progressively, with full rollout targeted by April 2031 (as announced at Budget 2026). For guidance on compliant software, see the IRAS InvoiceNow requirements page.

Financial support: SMEs can access a grant of up to S$1,000 to defray operational costs of adopting InvoiceNow-ready solutions. The Productivity Solutions Grant (PSG) also subsidises up to 50% of eligible software subscription costs.

How to Register for GST: Step-by-Step

Step 1: Determine Your Registration Trigger

Confirm whether you are registering due to retrospective turnover exceeding S$1 million, prospective belief that turnover will exceed S$1 million in the next 12 months, or voluntarily.

Step 2: Prepare Supporting Documents

You will need: your UEN (Unique Entity Number), financial statements or management accounts showing turnover, details of your business activities, and (for new voluntary registrants from 1 April 2026) details of your InvoiceNow-ready software.

Step 3: Submit Application via myTax Portal

Log in to mytax.iras.gov.sg using your Corppass credentials and complete the GST registration application. Processing typically takes 10 working days, though complex cases may take longer.

Step 4: Await Confirmation

IRAS will issue a GST registration number and confirm your effective date of registration. From this date, you must charge 9% GST on all taxable supplies and file GST returns quarterly.

Step 5: Set Up Accounting Systems

Update your invoicing templates to include your GST registration number and the GST amount separately. Ensure your accounting system can track output tax and input tax claims. For new voluntary registrants, set up InvoiceNow connectivity.

GST Filing Obligations After Registration

Once registered, you must file GST returns (Form F5 or F8) quarterly via myTax Portal and pay any net GST due by the deadline — typically one month after the end of each accounting period. The due date for filing and payment is the same.

Your company’s GST filing deadline is part of your broader annual compliance obligations. Our Singapore Company Compliance Calendar 2026 covers all key IRAS and ACRA filing dates. For corporate income tax obligations alongside GST, see our Singapore Corporate Tax 2026 guide.

Should You Register Voluntarily?

The decision to register voluntarily requires a cost-benefit analysis. Key factors to weigh:

  • Input tax recovery: How much GST do you pay on business purchases? If your input tax is substantial, voluntary registration may generate meaningful refunds.
  • Customer profile: If most of your clients are GST-registered businesses, they can reclaim the GST you charge — making you cost-neutral to them. If you serve predominantly non-registered consumers, adding 9% to your prices may affect competitiveness.
  • Administrative burden: GST registration requires quarterly filing, detailed record-keeping for five years, and (for new registrants from 2026) InvoiceNow compliance.
  • Two-year commitment: Once registered voluntarily, you cannot deregister for two years.

If you are uncertain whether voluntary registration makes sense for your business, the team at Raffles Corporate Services can help you assess your GST position and handle the registration process end-to-end.

— The Editorial Team, Raffles Corporate Services