When do you need to register for GST?

01Count taxable turnover
02Check both tests
03Apply to IRAS

Past turnover and your next 12 months are different tests.

Which check?

Last calendar year

If taxable turnover exceeded S$1 million, apply from 1 to 30 January the following year. Usual effective date: 1 March.

Next 12 months

If supported evidence forecasts more than S$1 million, apply within 30 days. For liability from 1 July 2025, the effective date is two months after the forecast date.

Below the threshold

Compare costs and conditions before volunteering. There are ongoing obligations, including a usual two-year minimum registration period.

Check the exceptions and InvoiceNow requirements below. These are different tests, not a decision based only on one sales figure.

GST registration is usually compulsory when taxable turnover exceeds S$1 million. That means taxable sales, not profit. Check both past sales and a supported forecast. IRAS explains the tests.

Start with the right sales total

Zero-rated sales count towards taxable turnover; exempt supplies, out-of-scope supplies and sales of capital assets do not. An individual combines their sole-proprietorship businesses and self-employed income for this check. A company assesses its own turnover.

Download your sales report. Classify unusual transactions before comparing the total.

Check the last calendar year

If taxable turnover exceeded S$1 million from 1 January to 31 December, apply between 1 and 30 January of the following year. The usual effective date is 1 March. An exception may apply where the next year's turnover will fall below the threshold, with supporting evidence.

Put the January check in your calendar, even if your financial year ends elsewhere.

Check the next 12 months

When a supported forecast exceeds S$1 million, apply within 30 days of the forecast date. For liability arising on or after 1 July 2025, registration takes effect two months from that date. Sales targets alone are not enough evidence.

Keep the contracts, confirmed orders and forecast that triggered the check.

Prepare before you charge

Use IRAS' application steps. Prepare the requested documents and confirm your effective date. Do not add GST to invoices before registration takes effect.

Test your invoice settings, quotations and bookkeeping with the person handling GST.

Below the threshold? Compare the trade-offs

Voluntary registration is not automatically a saving. Input-tax recovery has conditions. Registration also adds filing work and can affect consumer-facing prices. Voluntarily registered businesses must generally stay registered for at least two years.

Compare recoverable GST with pricing and administration costs before applying.

Check InvoiceNow too

Businesses applying for voluntary GST registration on or after 1 April 2026 must meet the GST InvoiceNow requirement, unless excluded. Other businesses enter in later phases. Do not assume a normal emailed PDF is enough.

Confirm your applicable phase and activate invoice-data submission to IRAS in your InvoiceNow-ready solution. An e-invoice connection alone is not enough. This overview covers ordinary Singapore businesses; overseas-vendor and reverse-charge rules need separate checks.