The practical takeaway
Monitor taxable turnover continuously — not only when preparing year-end accounts.
01 / Identify taxable turnover
GST is a transaction tax, and the relevant threshold looks at taxable supplies under IRAS rules. Not every receipt belongs in the turnover test. Obtain proper classification for exports, exempt supplies and cross-border business models.
02 / Understand the S$1 million threshold
A business generally must register for GST when taxable turnover exceeds S$1 million under the retrospective test, or when it reasonably expects taxable turnover to exceed S$1 million in the next 12 months under the prospective test. The two tests have different triggers and deadlines.
03 / Use the correct calendar
IRAS explains that the retrospective view assesses taxable supplies over the previous calendar year. Do not equate this with any arbitrary rolling 12-month figure without checking which rule applies. Keep documentation of forecasts and the evidence used at the time.
04 / Voluntary registration has consequences
Some businesses below the compulsory threshold may apply voluntarily, subject to conditions. Once registered, the company must follow invoicing, recordkeeping, return filing and payment obligations. Consider operational systems and potential cash-flow effects, not only input-tax recovery.
05 / Build a GST filing workflow
Most registered businesses file GST returns quarterly unless IRAS assigns a different cycle. Maintain reconciled sales and purchase records, correct tax codes and timely submission routines. Reassess international supplies and registration rules as the business model evolves.
Questions founders ask
What is the usual compulsory threshold?
S$1 million of taxable turnover under the relevant IRAS test.
Can you register voluntarily below the threshold?
Sometimes, subject to conditions and ongoing obligations.
Are GST and corporate income tax the same?
No. They are different regimes with different calculations and returns.
Primary sources
Regulatory rules change. Check the linked official guidance for your circumstances and the current filing period.
Editorial note: This independently prepared overview is educational and is not a substitute for regulated professional advice. No personal founder experience or service relationship is claimed.