Singapore GST InvoiceNow: The Peppol Mandate Explained for SaaS Sellers

Singapore is folding e-invoicing into the GST system itself. The GST InvoiceNow requirement, which began its phased rollout in November 2025, asks GST-registered businesses to send invoice data to the tax authority through InvoiceNow, the country's nationwide Peppol network. It is the same continuous-transaction-controls direction Europe and Latin America have taken, arriving in Southeast Asia through a network that already existed for business-to-business invoicing. This article explains how the pieces fit and what a foreign software seller should watch for.

Two things bundled into one requirement

It helps to separate the two layers that InvoiceNow combines:

• InvoiceNow is the e-invoicing network. Run under the Infocomm Media Development Authority (IMDA), it is Singapore's implementation of the Peppol framework: businesses exchange structured invoices through Access Points using the Peppol PINT SG specification, rather than emailing PDFs.
• The GST InvoiceNow requirement is the tax layer the Inland Revenue Authority of Singapore (IRAS) built on top. In-scope GST-registered businesses must transmit their invoice data to IRAS through the same network, giving the tax authority a structured feed of transactions close to real time.

If you have read the guides on Peppol for SaaS founders or the European mandates, the architecture will feel familiar. Singapore did not invent a new format. It connected the tax authority to a network firms were already encouraged to use.

The phased rollout

IRAS chose a soft-start approach that begins with the smallest, newest cohort rather than the largest taxpayers:

• Voluntary early adoption opened ahead of the formal dates for businesses that wanted to get ready.
• From November 2025, newly incorporated companies that register for GST voluntarily come into scope.
• From April 2026, the requirement extends to all new voluntary GST registrants, regardless of incorporation date.

IRAS has been explicit that this is a starting point and that scope will broaden over time. The sequencing matters: instead of forcing a large back book of established companies to retrofit their billing, Singapore is capturing businesses at the moment they register, when wiring up an InvoiceNow solution is part of setup rather than a migration.

The GST rate and what InvoiceNow does not change

Singapore's standard GST rate has been 9% since 1 January 2024 (it moved from 7% to 8% in 2023, then to 9%). InvoiceNow is a reporting and transmission mechanism. It does not change your rate, your registration obligation, or whether a given supply is taxable, zero-rated, or exempt. What it changes is the form in which you prove and report those decisions: structured data flowing through Access Points, not a PDF in an inbox.

Where overseas digital sellers fit

Foreign SaaS and digital-service vendors selling into Singapore generally engage with GST through the Overseas Vendor Registration (OVR) regime, which captures business-to-consumer supplies of digital and certain non-digital services to Singapore customers. Registration is triggered by global turnover and Singapore-specific sales thresholds, and registered overseas vendors charge 9% GST on in-scope B2C supplies.

The GST InvoiceNow requirement was designed first around domestically incorporated and locally registered businesses exchanging invoices on the network. Overseas vendors operating purely under OVR are in a different operational position: they typically issue receipts to consumers rather than structured B2B Peppol invoices to Singapore companies. The practical questions for a foreign seller are therefore:

• Do you have a Singapore establishment or local entity that registers for GST normally? If so, you are on the domestic track and the InvoiceNow timeline applies to you as it does to any local registrant in scope.
• Are you purely an OVR registrant with no local presence? Then your immediate obligation is correct OVR charging and reporting. Keep watching IRAS guidance, because the scope of who must transmit through InvoiceNow is expanding, and the line between OVR reporting and network-based reporting is exactly the kind of thing that gets revisited.

What you actually need to connect

For a business that is in scope, getting onto GST InvoiceNow means:

1. An InvoiceNow-Ready solution or an Access Point. You either use accounting or billing software that is certified InvoiceNow-Ready, or connect through a Peppol Access Point provider.
2. Peppol registration. Your business is identified on the network (commonly via your UEN) so invoices can be routed to and from you.
3. Activation of the IRAS feed. The step that distinguishes GST InvoiceNow from plain InvoiceNow is enabling transmission of invoice data to IRAS, so the tax authority receives the continuous feed.

The structured format means the same discipline good billing systems already need: a clean tax rate per line, a correct GST treatment, the right counterparty identifier, and totals that reconcile. Garbage in becomes garbage transmitted, and now the tax authority sees it directly.

Common misconceptions

1. "InvoiceNow is just a Singapore PDF replacement." It is a Peppol network with a tax-authority feed bolted on. The reporting dimension is the point.
2. "It only matters to new companies." That is where the rollout starts, not where it ends. IRAS has flagged broader scope ahead.
3. "As an overseas vendor I can ignore it." Maybe today, if you are purely OVR. But the moment you have a local entity, or IRAS widens scope, it is live for you. Know which track you are on.
4. "It changes my GST rate or registration test." It does not. 9% and the registration thresholds are unchanged; InvoiceNow is about transmission.

Frequently asked questions

What is GST InvoiceNow?

IRAS's requirement for in-scope GST-registered businesses to transmit invoice data to the tax authority through InvoiceNow, Singapore's Peppol-based e-invoicing network. It pairs B2B e-invoicing with a continuous feed to IRAS.

When does it start?

Phased from November 2025 for newly incorporated companies registering for GST voluntarily, and from April 2026 for all new voluntary GST registrants. Early voluntary adoption opened ahead of those dates, and IRAS plans to widen scope.

What is the GST rate in Singapore?

9%, in effect since 1 January 2024.

Does an overseas vendor under OVR have to use InvoiceNow?

The requirement was built first around locally registered businesses on the network. A pure OVR registrant's core obligation remains correct OVR charging and reporting, but the scope is expanding, so foreign sellers should track IRAS guidance and reassess if they gain a Singapore entity.