Start with taxable turnover, not cash collected.
The core threshold is taxable turnover above SGD 1 million. Taxable turnover is not the same as cash collected in the bank. It looks at supplies that count for GST purposes, and the question can be retrospective or prospective. A business that reasonably expects taxable turnover to exceed SGD 1 million in the next 12 months can become liable to register before the year is over.
- Monitor taxable supplies, not just bank receipts.
- Check both the past-period view and the forward-looking forecast view.
- Keep turnover workings in a form someone else can review later.
The prospective view needs evidence.
IRAS expects a forecast to be supported by real evidence. Signed contracts, accepted quotations, confirmed purchase orders, fixed-fee invoices, and income statements showing a clear trend are stronger than market estimates or sales targets. When the prospective test is met, the business should apply within 30 days after the forecast date. For forecasts made on or after 1 July 2025, IRAS states that registration is effective 2 months from the forecast date; check the current IRAS rule before relying on a date.
- Apply within 30 days after the forecast date when the prospective test is met.
- For forecasts on or after 1 July 2025, plan for the registration to be effective 2 months from the forecast date, subject to current IRAS guidance.
- Use signed or accepted documents as the forecast basis where possible.
- Do not treat an unsupported sales target as registration evidence.
Voluntary registration is an operating decision.
A business below the threshold may still choose voluntary registration. The usual reasons are input-tax recovery, mostly GST-registered customers, or a desire to prepare early for growth. The tradeoff is real: once registered, the business has to charge GST, issue compliant tax invoices, file GST returns, and keep records properly.
- Voluntary registration can help recover eligible input tax.
- It can create pricing friction for non-GST-registered customers.
- It adds ongoing filing, invoice, and record-keeping obligations.
Prepare before the effective date.
The messy part is not the form. It is making sure invoices, tax codes, source documents, customer pricing, and review responsibilities are ready before GST starts appearing on transactions. A clean setup reduces quarter-end reconstruction when the first F5 comes due.
- Set up GST tax codes and invoice wording before charging GST.
- Decide who reviews blocked input tax, zero-rated supplies, and exempt supplies.
- Keep source documents attached to transactions from day one.
- Plan the F5 review workflow before the first quarter closes.
How Accountant Included fits.
Accountant Included is being built to help the SME keep the evidence trail clean: turnover monitoring, source documents, GST treatment drafts, review-queue exceptions, and F5 review packs. It does not decide your registration position for you and it does not file on your behalf. The useful product role is to make the evidence and review trail easier to inspect.