Singapore GST InvoiceNow: An Implementation Plan for Finance Teams

A business can send invoices through InvoiceNow without submitting their data to the Inland Revenue Authority of Singapore (IRAS). The GST submission feature must be activated separately. Finance teams should therefore treat implementation as a reporting project, not simply an electronic-invoicing upgrade.2

InvoiceNow uses the Peppol network to exchange structured invoices between finance systems. The Goods and Services Tax (GST) requirement adds invoice-data transmission to IRAS.4 Start by confirming your entity’s deadline, identifying the data each system holds and assigning responsibility for successful submissions. Whether the business needs GST registration is a separate question, covered in our Singapore GST registration guide.

Confirm the applicable phase before setting the project date

As at 10 November 2026, two phases have already started. From 1 November 2025, the requirement applies to companies applying for voluntary GST registration within six months of incorporation. From 1 April 2026, it applies to businesses applying for voluntary GST registration regardless of incorporation date or business structure.2

IRAS announced the wider rollout on 26 February 2026. The following are future mandatory implementation dates in the official schedule, not dates on which every existing registrant is already required to transmit:1

• 1 April 2028: businesses applying for compulsory GST registration on or after this date, plus existing GST-registered businesses with total annual supplies of no more than SGD 200,000.
• 1 April 2029: remaining existing GST-registered businesses with total annual supplies above SGD 200,000 and no more than SGD 1,000,000.
• 1 April 2030: remaining existing GST-registered businesses with total annual supplies above SGD 1,000,000 and no more than SGD 4,000,000.
• 1 April 2031: existing GST-registered businesses with total annual supplies above SGD 4,000,000.1 2

For this phasing exercise, total annual supplies include standard-rated, zero-rated and exempt supplies in GST accounting periods ending in calendar year 2025. This is not simply the latest financial-year revenue figure. Businesses with incomplete periods may need the guide’s annualisation method.3 Keep the supporting calculation with the entity’s IRAS implementation notification. Where the baseline is unavailable or the applicable date is unclear, obtain clarification from IRAS rather than assigning a date from current sales.

Separate entity exemptions from excluded transactions

Foreign ownership does not itself create an exemption. The excluded overseas-entity category includes overseas businesses required to appoint local section 33(1) agents and vendors under the Overseas Vendor Registration regimes. A foreign-incorporated business with a Singapore branch or establishment is not treated as an excluded overseas entity for this purpose. Neither is a Singapore business with an overseas branch.3

Businesses liable to register for GST wholly because of the reverse charge regime are also excluded. A normally registered business that happens to have reverse charge transactions must still comply. Small size, low transaction volume or supplying only related entities does not provide a general exemption.2 3

Document the entity-level conclusion first. Then decide which transactions require transmission. Confusing these two assessments can leave an otherwise covered company’s entire reporting flow switched off.

Choose a supported connection and activate submission

For off-the-shelf software, check IMDA’s accredited InvoiceNow-Ready Solution Provider list through the official InvoiceNow guidance. For a customised enterprise resource planning (ERP) system, engage an IMDA-accredited Access Point Provider to connect it to the network. Your provider registers the business in the SG Peppol Directory using its Unique Entity Number (UEN) and obtains its Peppol ID. The GST InvoiceNow submission feature must then be enabled.4

Singapore-registered businesses need Corppass for the onboarding identity-check process.5 Arrange this early, but keep the wider access-delegation review separate from the technical integration.

Before selecting a package, ask the provider to demonstrate sales and purchase submissions, credit notes, rejected-data handling and retrieval of IRAS acknowledgement IDs. Confirm what is included in the subscription and what requires integration work. Accreditation is the starting point; your actual transaction flows still need testing. IRAS provides a sandbox environment through the providers for integration and submission testing.2

Map more than invoices sent to customers

The scope generally covers standard-rated and zero-rated supplies and purchases, together with exempt supplies reported in GST returns. It includes invoices and equivalent billing or adjustment documents, such as receipts and credit notes. Specified exclusions include reverse charge transactions, import permits, deemed supplies and exempt financial services.3

Purchase reporting needs its own workflow. A supplier’s transmission of sales data does not discharge the buyer’s purchase-data obligation. The purchase submission can contain additional information, including input tax claimed. Purchases from GST-registered suppliers where input tax is not claimed fall outside the requirement, although voluntary transmission is permitted using the appropriate category code.2

There are two important operational routes:

• Peppol sales invoices: when both parties are connected and the submission feature is enabled, IRAS receives a copy as the invoice is sent through the network.
• Solution-extracted data: invoices issued outside the network, including paper or PDF invoices, and recorded purchase invoices are submitted from the InvoiceNow-Ready Solution.2

Do not assume that emailing a PDF to an Access Point Provider creates compliant invoice data. IRAS requires the information to be recorded and submitted through the solution-extracted route. Permitted aggregation for point-of-sale sales, simplified tax invoices and petty cash purchases should be configured deliberately, not applied indiscriminately.2

For regional groups, map existing internal tax codes to IRAS’s accepted codes. Invoice data required for GST reporting in foreign currencies must be converted to SGD using approved exchange rates. Where invoicing and accounting systems use different references, the invoice number transmitted must reflect the document issued to the customer, not a separate internal accounting reference.2

Make successful transmission a pre-filing control

Invoice data must reach IRAS by the earlier of the date the relevant GST return is filed or its filing deadline. Filing early therefore brings the transmission deadline forward.2 Add this dependency to the company’s annual compliance calendar.

Build a reconciliation between the source ledger, submitted records and IRAS acknowledgements. An acknowledgement ID confirms receipt; it does not establish that the underlying GST treatment is correct.2 Assign an owner to investigate missing or rejected submissions before the return is released.

The reconciliation need not force an artificial exact match. IRAS recognises legitimate differences, including timing and input-tax apportionment. Retain an explanation supported by records. InvoiceNow does not replace GST returns or the obligation to keep proper records, including source documents, for at least five years.2

Readiness checklist

Before switching to routine production reporting, confirm that:

• The entity’s phase and exemption assessment are documented.
• Its Peppol registration and GST submission feature are active.
• Sales, purchases and adjustment flows pass end-to-end tests.
• Tax-code mapping, currency conversion and invoice references are approved by finance.
• Staff can retrieve acknowledgements and resolve rejected records before filing.
• Source documents and structured invoice records remain accessible for retention and audit.

Focused FAQs

Can an overseas shared service centre submit for the Singapore company?

Yes. It can use a suitable InvoiceNow-Ready Solution or connect its enterprise system through an accredited Access Point Provider. The Singapore GST-registered supplier must be correctly identified in the invoice data, including its UEN.2 For a regional group, distinguish this operational delegation from the Singapore holding-company and Vietnam operating-company structure.

Can a shared ERP project justify postponing implementation?

Not automatically. IRAS’s October 2026 FAQ allows businesses in commercial arrangements using a shared ERP system to request an extension, with reasons and supporting documents. IRAS considers requests individually.2 Continue planning against the assigned date unless an extension is confirmed.

References

• 1 IRAS, Committee of Supply 2026: Extension of GST InvoiceNow Requirement to All GST-registered Businesses by April 2031, 26 February 2026
• 2 IRAS, Frequently Asked Questions for GST InvoiceNow Requirement, version 26 October 2026
• 3 IRAS e-Tax Guide, Adopting GST InvoiceNow Requirement for GST-Registered Businesses, second edition, 9 March 2026
• 4 IRAS, Getting Started with the GST Requirement: A Guide for Businesses, 24 June 2026
• 5 IMDA, InvoiceNow, last updated 8 June 2026