GST registration, filing and InvoiceNow — Step-by-step walkthrough

GST registration, filing and InvoiceNow set the rhythm of Singapore indirect-tax compliance: register once turnover crosses S$1 million, charge and account for GST at 9 per cent, file accurate returns each period, and move to InvoiceNow e-invoicing. This step-by-step walkthrough covers thresholds, deadlines, costs and common errors.

What GST registration, filing and InvoiceNow involve

Goods and Services Tax is Singapore’s broad-based consumption tax, charged at 9 per cent since 1 January 2024. A registered business charges GST on its taxable supplies (output tax), claims back GST on its purchases (input tax), and remits the net to the Comptroller. InvoiceNow is the nationwide e-invoicing network based on the international Peppol standard, which the authorities are progressively requiring GST-registered businesses to adopt for transmitting invoice data.

The framework sits within the Goods and Services Tax Act 1993, which defines taxable supplies, registration liability and input-tax recovery. For the corporate-tax side of the picture, see Single vs Multi-Family Office in Singapore (2026): Costs, Pros and Cons; where GST interacts with foreign-worker costs and pass administration, DP → EP and DP → LOC conversion routes — Step-by-step walkthrough is a useful cross-reference.

Who must register, and the S$1 million threshold

Registration is compulsory under the retrospective test when taxable turnover exceeds S$1 million in the past calendar year, and under the prospective test when you reasonably expect to exceed S$1 million in the next twelve months. Businesses below the threshold may register voluntarily to recover input tax, subject to staying registered for at least two years. Failing to register on time is a common and penalised error.

Filing periods, deadlines and the GST F5

Most registered businesses file the GST F5 return quarterly, within one month after the end of each accounting period. The return reports output tax, input tax and the net payable or refundable. Payment is due by the same deadline; GIRO arrangements are widely used. Late filing or payment attracts penalties and can trigger a 5 per cent late-payment surcharge with further additions for continued default, as administered by IRAS.

Cost, timeline and step-by-step process

Indicative figures and sequence:

• Registration: free to apply; processing commonly takes up to a few weeks once documents are complete.
• GST rate: 9 per cent on standard-rated supplies.
• Filing frequency: quarterly F5 by default; monthly available on request.
• Accounting-software or InvoiceNow set-up: budget S$0 to S$3,000 depending on your system.

Run it in order: (1) test your turnover against both thresholds; (2) apply via the myTax portal; (3) configure your accounting system to charge and track GST; (4) connect to InvoiceNow through a Peppol-ready solution; (5) file each F5 on time; (6) keep tax invoices and records for five years. These registration, charging and input-tax-recovery rules all flow from the Goods and Services Tax Act 1993. Our detailed companion at GST registration, filing and InvoiceNow — Complete 2026 guide expands each step.

InvoiceNow adoption

InvoiceNow lets businesses send structured e-invoices directly between accounting systems over the Peppol network, reducing manual entry and speeding up GST data submission. Singapore is phasing in a requirement for GST-registered businesses to transmit invoice data via InvoiceNow, beginning with newly incorporated voluntary registrants and expanding over time. Adopting early reduces disruption; choose accounting software that is already InvoiceNow-ready and register your participant identifier.

Common mistakes and gotchas

Typical errors include missing the registration deadline after crossing S$1 million, reclaiming input tax on blocked items such as private motor-car expenses and most client entertainment, issuing invoices without the required tax-invoice fields, and forgetting to charge GST on deemed supplies. Reporting standards for the underlying accounts are set by the ACRA accounting standards, and statutory filing of financial statements runs through ACRA. Reconcile your GST returns to your ledgers every period to catch errors before filing.

Output tax, input tax and how the net is computed

The mechanics of GST are simpler than they first appear once you separate the two flows. Output tax is the 9 per cent you charge customers on standard-rated supplies. Input tax is the 9 per cent you pay suppliers on business purchases. Each period you total both, and you remit the excess of output over input, or claim a refund where input exceeds output. A business in a refund position, such as an exporter making zero-rated supplies, can receive money back, which is one reason exporters often register voluntarily.

Supplies fall into categories that change the treatment. Standard-rated supplies carry 9 per cent. Zero-rated supplies, mainly exports and international services, carry GST at 0 per cent but still allow input-tax recovery. Exempt supplies, such as most financial services and the sale and lease of residential property, carry no GST and generally block input-tax recovery on related costs. Misclassifying a supply is one of the most common and costly GST errors, so a clear mapping of your revenue lines to these categories belongs in your accounting set-up.

Tax invoices, records and the five-year rule

A valid tax invoice is the document that lets your customer claim input tax and that supports your own output-tax position. It must show your GST registration number, an invoice date and number, the customer’s details, a description of the supply, and the GST amount and rate. For supplies of S$1,000 or less a simplified tax invoice is acceptable. Every tax invoice, credit note and import permit must be retained for five years, because the Comptroller can review past periods within that window.

Good record-keeping is also what makes period-end painless. If your ledger is configured to tag each transaction with the correct GST code, the F5 figures fall out automatically and reconcile to your accounts. Where you rely on spreadsheets or manual coding, build in a reconciliation step so that the GST control account agrees to the return before you file.

Preparing for InvoiceNow adoption

InvoiceNow is more than a compliance requirement; it is an operational upgrade. Because invoices travel as structured data over the Peppol network directly between accounting systems, there is less manual entry, fewer disputes over invoice details, and faster settlement. The practical preparation is to choose accounting software that is already InvoiceNow-ready, register your Peppol identifier, and test sending and receiving with a few counterparties before relying on it for live filing.

Businesses that move early avoid a last-minute scramble when their category’s deadline arrives. They also gain the cash-flow and accuracy benefits sooner. Treat the transition as a small project with a defined go-live date rather than a box to tick at the eleventh hour.

Worked example: a growing trading SME

Imagine a trading company whose taxable turnover crosses S$1 million in October. It must register, and once registered it charges 9 per cent on local sales and zero-rates its exports. In a typical quarter it might collect S$45,000 of output tax on local sales, pay S$30,000 of input tax on purchases and overheads, and so remit S$15,000 with its F5. Its exports, being zero-rated, add no output tax but still allow the related input tax to be reclaimed, which can tip a heavy-export quarter into a net refund. Configuring the accounting system correctly from day one is what makes this routine rather than stressful.

Related guides and where to go next

GST sits alongside corporate tax and employment-cost planning. For the corporate-tax dimension, Single vs Multi-Family Office in Singapore (2026): Costs, Pros and Cons is a useful companion, and where foreign-worker costs feature, DP → EP and DP → LOC conversion routes — Step-by-step walkthrough is directly relevant. Our deeper walkthrough at GST registration, filing and InvoiceNow — Complete 2026 guide sets out the F5 line-by-line with InvoiceNow set-up steps.

FAQs

What is the GST rate in 2026? The standard rate is 9 per cent, in force since 1 January 2024.

When must I register? When taxable turnover exceeds S$1 million in the past year, or is expected to exceed it in the next twelve months.

How often do I file? Quarterly by default via the GST F5, due one month after each period ends; monthly filing is available on request.

Is InvoiceNow mandatory? It is being phased in for GST-registered businesses; check your category and timeline on IRAS and adopt a Peppol-ready system early.

Can I claim all input tax? No. Certain items are blocked, including most entertainment and private car expenses; only valid business input tax with proper tax invoices is claimable.

Need help with this? Call, SMS or WhatsApp +65 8501 7133, or email [email protected]. Raffles Corporate Services works with a panel of corporate and employment law firms; this article is general information, not legal advice.