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When GST registration is required

Last updated: July 2026

Short answer

Taxable turnover over S$1 million requires GST registration (rate 9%), tested two ways. Below the threshold, registration is voluntary. Retrospective: if turnover over the past 12 months exceeds S$1M at any calendar year-end, apply within 30 days. Prospective: if you reasonably expect the next 12 months to exceed S$1M (e.g. a signed large contract), also apply within 30 days. From April 2026, all new voluntary registrants must use the InvoiceNow e-invoicing system.

Threshold and deadlines

TestTriggerDeadline
RetrospectiveAt any calendar year-end, past 12 months' taxable turnover > S$1MApply within 30 days of year-end
ProspectiveReasonable grounds to expect next 12 months > S$1M (e.g. signed contract)Apply within 30 days of forming that expectation
VoluntaryBelow S$1MOptional, must stay registered ≥2 years
GST rate9% (since January 2024)

Retrospective vs prospective

Retrospective: looks back. At each calendar year-end (Jan-Dec), review the past 12 months' taxable turnover; if over S$1M, apply within 30 days. Example: 2026 taxable turnover of S$1.1M means applying by 30 January 2027, with registration effective 1 March.

Prospective: looks forward. If you reasonably expect the next 12 months to exceed S$1M — typically after signing a contract that alone crosses the threshold — apply within 30 days of forming that expectation. Note IRAS's phrase "reasonable grounds": a signed master service agreement with a defined value counts; a mere pipeline forecast does not.

What "taxable turnover" means

The threshold is on taxable turnover, not total revenue. Taxable turnover is supplies that would attract GST if you were registered — standard-rated and zero-rated supplies — but not exempt supplies (like residential rent or certain financial services). Knowing what counts is essential to judge whether you must register.

The 2026 InvoiceNow rule

The key recent change: from April 2026, all new voluntary GST registrants must transmit invoice data to IRAS through the InvoiceNow (Peppol) network. This phases in — April 2028 covers new compulsory registrants and existing GST businesses with annual supplies at or below S$200,000, April 2029 covers those at or below S$1M, reaching all GST businesses by 2031. If you plan to register voluntarily, prepare InvoiceNow-ready accounting software early.

Is voluntary registration worth it

You can register voluntarily below the threshold. The benefit is claiming input tax — useful if your customers are mostly GST-registered. But note two things: once voluntarily registered you must stay for at least 2 years; and from April 2026 voluntary registration means InvoiceNow. Whether it's worth it depends on your customer mix and compliance cost.

Common misconceptions

"The threshold is on total revenue"

It is on taxable turnover; exempt supplies (like residential rent) do not count.

"I can register slowly after crossing"

There is a 30-day deadline. Late, IRAS can backdate registration, recover GST you never collected, and fine you.

"Voluntary registration has no extra burden"

From April 2026 voluntary registration requires InvoiceNow and a 2-year minimum.

How we handle it

We judge whether taxable turnover crosses the threshold, whether the retrospective or prospective test applies, when you must file, and whether voluntary registration is worth it and how to prepare InvoiceNow. See company registration; annual tax duties in what every company must do each year.

Frequently asked

At what turnover must I register for GST?

Taxable turnover over S$1M. Two tests — retrospective (past 12 months) and prospective (expected next 12 months) — with 30 days to apply after triggering.

What is the GST rate?

9%, since January 2024 (previously raised in two stages from 7% to 8% then 9%).

Can I register below the threshold?

Yes, voluntarily — you can claim input tax, useful if customers are GST-registered. But you must stay ≥2 years, and from April 2026 must use InvoiceNow.

What is InvoiceNow and who does it affect?

IRAS's e-invoicing system (Peppol network). From April 2026 all new voluntary registrants must use it, phasing in to all GST businesses.

What if I miss the deadline after crossing?

There is a 30-day window. Late, IRAS can backdate registration, recover historical GST you never collected, and add penalties.

Sources: IRAS (GST thresholds, retrospective/prospective tests, 9% rate, phased InvoiceNow). Verified July 2026; follow IRAS's latest. General information, not tax advice.

Unsure whether to register for GST?

Whether turnover crosses the threshold, which test applies and when to file — we judge it, and assess whether voluntary registration is worth it.

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