Singapore e-invoicing: the complete guide for businesses

TL;DR summary

• Singapore is extending its existing InvoiceNow (Peppol) network into a conceptual five‑corner model, where the same GST‑relevant invoice feeds two paths: business‑to‑business exchange via InvoiceNow and tax data submission to IRAS.
• Invoice delivery to buyers happens via InvoiceNow (Peppol) using the PINT SG profile based on UBL 2.1.
• GST reporting to IRAS happens via separate IRAS/APEX APIs, using an IRAS‑defined JSON data schema derived from the underlying invoice data rather than the Peppol document itself.
• IRAS is not a Peppol endpoint; IMDA‑accredited Peppol Access Points and connected solutions orchestrate both the InvoiceNow exchange and the API‑based tax data submission.
• Businesses must support multiple document types, including tax invoices, credit notes, debit notes, simplified invoices, aggregated POS summaries and self‑billed invoices, and ensure that GST‑relevant data for these documents is correctly mapped into IRAS’s JSON schema.

What is e‑invoicing in Singapore?

Singapore has been an early adopter of Peppol‑based e‑invoicing through the InvoiceNow network. With the GST InvoiceNow Requirement, the country is taking the next step towards near real‑time GST visibility for the tax authority.

At a high level, the reform aims to:

• Reduce manual handling and invoicing errors
• Improve data quality for GST reporting
• Streamline compliance for GST‑registered businesses
• Support a more digital, automated tax environment

Instead of invoices existing only between supplier and buyer, GST‑relevant data is now also routed to IRAS. To achieve this without creating a bottleneck at the tax authority, Singapore is expanding the classic Peppol four‑corner model into a five‑corner framework that introduces IRAS as an additional recipient of invoice data.

For businesses, this has two main implications:

• Structured invoices become the norm. GST‑relevant invoices must follow the PINT SG profile based on UBL 2.1.
• Connectivity matters more than ever. You need a reliable way to connect both to trading partners and to IRAS via an IMDA‑accredited Access Point.

What role does InvoiceNow play?

InvoiceNow is Singapore’s implementation of the Peppol network, coordinated by the Infocomm Media Development Authority (IMDA). It already enables structured invoice exchange between businesses via IMDA‑accredited Access Points.

Under the GST InvoiceNow Requirement, InvoiceNow remains the backbone for business invoice delivery, while the resulting invoice data is also used for GST reporting:

• Businesses connect once to an InvoiceNow‑ready solution/Access Point.
• Invoices are created in the PINT SG format and routed via the InvoiceNow network to buyers.
• From these same invoices, relevant data elements are extracted and mapped into an IRAS‑defined JSON structure, which is then submitted to IRAS via the APEX/Invoice Data Submission APIs.

In other words, InvoiceNow is the primary channel for B2B invoice exchange, while IRAS receives structured JSON payloads built from the same source invoices rather than the Peppol documents themselves.

How Peppol fits into the national model

Singapore’s model builds directly on the standard Peppol four‑corner architecture, in which invoices flow from supplier to buyer via their respective Access Points. The GST InvoiceNow Requirement extends this into a conceptual five‑corner set‑up by introducing IRAS as an additional consumer of tax‑relevant data, even though IRAS does not act as a Peppol endpoint.

For readers who want more background on Peppol itself, the roles of IMDA and the evolution of InvoiceNow, we recommend our dedicated explainer on Peppol in Singapore: InvoiceNow, IMDA and the GST Integration.

In practice, the national model results in several standardised flows, often referred to as Flows A–F. They cover both outbound and inbound scenarios and support Peppol and non‑Peppol exchanges as well as aggregated data, with IRAS receiving GST‑relevant information via API as JSON rather than via Peppol messages.

Outbound flows (supplier perspective)

Flow A: Peppol invoice + IRAS submission

• Supplier sends an invoice from their ERP to an Access Point such as ecosio.
• The Access Point delivers the invoice to the buyer via the InvoiceNow (Peppol) network in PINT SG format.
• At the same time, the Access Point submits a copy of the same invoice in JSON format to IRAS via the dedicated Invoice Data Submission API.

Flow B: Non‑Peppol invoice + IRAS submission

• The business exchanges invoices with the buyer outside Peppol (for example via EDI or email).
• Relevant invoice data is extracted and transformed into PINT SG by the Access Point or solution provider.
• The Access Point submits the invoice data as JSON directly to IRAS (no delivery to the buyer in this flow).

Flow C: Aggregated POS and petty‑cash transactions

• High‑volume B2C or petty‑cash transactions are aggregated into summaries.
• These summaries are sent to the Access Point, which creates a single aggregated PINT SG invoice.
• The Access Point submits the invoice data as JSON directly to IRAS only.

Inbound flows (buyer perspective)

Flow D: Peppol invoice received + IRAS submission

• The supplier sends a Peppol PINT SG invoice via InvoiceNow.
• The buyer’s Access Point receives the invoice and delivers it to the buyer’s ERP or AP system.
• The invoice data is also submitted to IRAS as JSON for GST reporting purposes.

Flow E: Non‑Peppol invoice + IRAS submission

• The buyer receives an invoice by email or EDI.
• The buyer or their solution provider passes the data to the Access Point.
• The Access Point transforms the data into PINT SG and submits invoice data to IRAS as JSON.

Flow F: Aggregated invoices received

• The buyer aggregates POS receipts or petty‑cash transactions on their side.
• The aggregated data is sent to the Access Point.
• The Access Point creates a PINT SG aggregated invoice and submits invoice data to IRAS as JSON.

Across all these flows, the goal is consistent: GST‑relevant invoice data is delivered in a structured, standardised format to IRAS without disrupting business‑to‑business exchange.

What is voluntary today *versus* directionally mandatory tomorrow?

The GST InvoiceNow Requirement is being introduced gradually, starting with voluntary participation and moving to mandatory phases for certain taxpayers.

Key milestones

In the short term, many businesses can still join on a voluntary basis. However, the direction is clear:

• New voluntary GST registrants are already moving into mandatory submission territory.
• In a future phase, the scope is expected to expand to all GST‑registered businesses, turning today’s best practice into tomorrow’s obligation.

Alongside these mandate dates, there are also important requirements around record keeping. As under the Goods and Services Tax (General) Regulations, invoice records must be retained for at least five years, whether stored in paper or electronic form. Electronic records must remain accessible and readable for audit purposes, even if they are stored outside Singapore.

How Singapore differs from clearance‑based countries

From a distance, Singapore’s GST InvoiceNow Requirement can look similar to clearance‑based e‑invoicing models used in other regions. However, there are important differences:

• Singapore leverages the existing Peppol/InvoiceNow network, rather than routing all invoices through a single central tax portal.
• IRAS is added as a fifth corner in a Peppol‑based model, instead of acting as the sole intermediary in every transaction.
• IMDA‑accredited Access Points remain central to both B2B delivery and tax data submission, giving businesses more flexibility in how they connect.
• Flows B, C, E and F show that non‑Peppol exchanges (EDI, email, POS summaries) are still possible, provided the data is ultimately transformed into PINT SG and submitted to IRAS.

For multinational groups, this makes Singapore more similar to a network‑driven reporting regime than to classic real‑time clearance systems seen in some Latin American or European countries.

Involved parties: Access Points, IRSPs and IRAS

The five‑corner model introduces clear roles and responsibilities for each party involved in the GST InvoiceNow Requirement.

IMDA‑accredited Access Points (APs)

Access Points are at the heart of the model. They must be accredited by Singapore’s Infocomm Media Development Authority (IMDA) and are responsible for:

• Providing connectivity to the InvoiceNow (Peppol) network
• Submitting GST‑relevant invoice data to IRAS via API
• Managing CorpPass‑based activation for GST‑registered businesses
• Tracking submissions and returning acknowledgements and status updates

From a business point of view, an Access Point acts as the gateway to both trading partners and IRAS. Without an accredited AP, you cannot meet the submission requirements of the GST InvoiceNow mandate.

InvoiceNow‑Ready Solution Providers (IRSPs)

IRSPs are software vendors such as ERPs, billing platforms or accounting systems that create and manage invoice data for their customers. They:

• Help businesses generate invoices, credit notes and summaries in line with PINT SG requirements
• Integrate with one or more Access Points to deliver and submit invoice data
• Implement validations such as GST registration checks and UUID handling

Unlike Access Points, IRSPs do not connect directly to IRAS. Instead, they rely on an accredited Access Point to submit tax data on behalf of their customers.

IRAS as the fifth corner

The Inland Revenue Authority of Singapore acts as the fifth corner in the overall model. IRAS:

• Receives invoice data in PINT SG format via the Invoice Data Submission API
• Validates submissions using Schematron‑based business rules
• Issues acknowledgement IDs and status responses
• Provides detailed error messages where submissions fail validation

Together, these roles ensure that invoice data is both exchangeable between businesses and usable for GST reporting.

Document types and formats in scope

The GST InvoiceNow Requirement covers a broad range of documents, as long as they are GST‑relevant and fall within domestic B2B or B2G scope.

Supported document types

Key document types include:

• Tax invoices: standard invoices for taxable supplies
• Credit notes: used to reduce the value of a previous invoice
• Debit notes: used where an invoice needs to be increased
• Simplified tax invoices: low‑value invoices (≤ SGD 1,000) with reduced data requirements
• Aggregated invoices: summaries of many small B2C or petty‑cash transactions, typically coming from POS systems
• Self‑billed invoices: invoices issued by the buyer on behalf of the supplier under a pre‑agreed arrangement

All of these documents must be submitted to IRAS in PINT SG format when they are within scope of the requirement.

How ecosio supports Singapore’s GST InvoiceNow Requirement

For many businesses, building and maintaining a custom integration with both Peppol and IRAS would be complex, especially as rules and timelines evolve. This is where a specialised provider can make a difference.

ecosio’s e‑invoicing solution for Singapore is designed to provide:

• Dual delivery to buyers and IRAS from a single connection
• Automatic transformation of inbound data into PINT SG
• Pre‑submission validation against IRAS Schematron rules
• Integration with existing ERPs and financial systems via API, SFTP or other channels
• Full visibility into Peppol and IRAS flows via ecosio Monitor

By connecting once to ecosio, businesses can comply with both the InvoiceNow network and the GST InvoiceNow Requirement while keeping their internal systems as simple as possible.

Getting ready for the next phases

Although not all GST‑registered businesses are immediately in scope, the direction of travel is clear: structured e‑invoicing and electronic tax reporting will become standard practice in Singapore.

To prepare, organisations should:

• Assess whether they fall into one of the early mandate phases
• Review current invoicing channels and volumes
• Identify where GST‑relevant data is generated and stored
• Plan how to connect to an IMDA‑accredited Access Point
• Consider how to handle non‑Peppol and aggregated scenarios

Taking these steps early helps avoid last‑minute projects and reduces the risk of non‑compliance once the mandate expands to all GST‑registered businesses.

Ready to explore Singapore e‑invoicing in more detail?

If you’d like to understand how the GST InvoiceNow Requirement impacts your specific setup or how to connect your existing systems to InvoiceNow and IRAS, [feel free to contact us](https://ecosio.com/en/get-in-touch/). Our experts would be more than happy to discuss your options with you.

Stay informed

Ensure you’re always aware of the latest developments in Singapore e-invoicing. ecosio offers several channels to help you track regulatory changes…

E-invoicing updates newsletter – Join our mailing list for the latest regulatory insights, practical guidance and useful resources on e-invoicing

Singapore compliance overview page – An in-depth guide to the current rules and obligations

E-invoicing deadlines calendar – Track upcoming mandates and regulatory milestones with our comprehensive deadline tool

Frequently asked questions

Is e-invoicing mandatory in Singapore today?

Not for all businesses. The first phases focus on voluntary participation and on new voluntary GST registrants. However, a future phase is expected to extend the requirement to all GST-registered businesses.

Do I have to use Peppol / InvoiceNow?

To use the standard five-corner model and submit invoice data automatically to IRAS, businesses are expected to use InvoiceNow via an IMDA-accredited Access Point. Non-Peppol channels can still be used for business exchange, but GST-relevant data must ultimately be transformed into PINT SG and submitted to IRAS.

How does this affect my existing EDI or PDF processes?

You can often retain existing EDI or PDF channels towards trading partners. The key change is that GST-relevant data must also be sent in structured form (PINT SG) to IRAS. This is typically handled by your e-invoicing or integration provider.

What if my ERP is not InvoiceNow-ready?

If your ERP is not an InvoiceNow-Ready Solution Provider (IRSP), you can still comply by working with an external Access Point provider that handles PINT SG mapping, validation and submission on your behalf.

What happens if a submission fails?

IRAS returns an acknowledgement and error codes where validation fails. Your provider should surface these errors, help you understand the root cause and support re-submission once the data has been corrected.

Want more information on Singapore?

At ecosio we specialise in simplifying e-invoicing compliance globally. Our managed connectivity and API integrations support InvoiceNow and Peppol-based exchanges, helping businesses transform GST-relevant data into PINT SG and submit it to IRAS with full transparency and control.

• Learn about the benefits of e-invoicing
• Talk to us about e-invoicing in Singapore: contact us