What does InvoiceNow integration mean for a Singapore business?
InvoiceNow integration means connecting the software that creates your invoices to the InvoiceNow network so they travel as structured data rather than as PDFs. InvoiceNow is Singapore's nationwide e-invoicing network, based on the international Peppol standard and managed by IMDA as Singapore's Peppol Authority.
The IRAS e-Tax Guide on the GST InvoiceNow Requirement is blunt on one point: emailing PDF invoices is not e-invoicing, because the customer still has to type the details into their own system. With InvoiceNow, the invoice lands directly in the customer's finance software, and under the GST requirement, IRAS receives the invoice data too.
Most businesses meet this by using accounting software that is already InvoiceNow-Ready. InvoiceNow integration becomes a project when invoices are created somewhere else: a custom order management platform, a subscription billing system, an online store with its own invoicing, or an in-house ERP that no vendor supports. That is the work this page covers.
Who must use InvoiceNow, and from when?
IRAS is phasing the requirement in by type of registration and business size. The IRAS e-Tax Guide on adopting the GST InvoiceNow Requirement (published 9 March 2026) sets out these phases.
- From 1 Nov 2025: newly incorporated companies that register for GST voluntarily, where incorporation is within six months of the application.
- From 1 Apr 2026: all new voluntary GST registrants, regardless of incorporation date or structure.
- From 1 Apr 2028: new compulsory GST registrants, and existing GST-registered businesses with total annual supplies of 200,000 Singapore dollars or less.
- From 1 Apr 2029: existing GST-registered businesses with total annual supplies up to S$1 million.
- From 1 Apr 2030: existing GST-registered businesses with total annual supplies up to S$4 million.
- From 1 Apr 2031: all remaining GST-registered businesses with supplies above S$4 million.
Supplies are measured over the prescribed accounting periods ending in calendar year 2025. The guide notes that legislation for the remaining businesses will be enacted later, that voluntary registrants who fail to comply may have their registration revoked, and that certain overseas entities and businesses registered solely because of reverse charge are excluded. IRAS also offers an implementation date calculator. Your accountant should confirm which phase applies to you; we plan the InvoiceNow integration timeline around that date.
What invoice data has to reach IRAS through InvoiceNow?
Data from documents that serve as a bill for payment, for both supplies and purchases, including credit notes. The e-Tax Guide lists sales invoices, tax invoices, simplified tax invoices, serially numbered receipts, debit notes and credit notes as invoice data, while sales orders, pro-forma invoices and statements of account are not.
That scope surprises many teams. Purchases count too, so an InvoiceNow integration for a custom system is not only about outgoing invoices; purchase records need to reach IRAS as well. The guide also says that where a business would normally issue an invoice but does not, for example related entities settling by offsetting balances, the recorded data must still be submitted.
Each record carries mandatory elements such as supplier and customer identifiers, amounts and GST category codes. For customers, the guide requires the customer's UEN, name and address in most cases, with an overseas registration number for foreign entities without a UEN and “NA” for individuals trading under their personal name. Point-of-sale transactions, simplified tax invoices and petty cash purchases are treated differently.
Access Point or InvoiceNow-Ready Solution: which route suits your system?
If your invoicing lives in an accounting package, use an InvoiceNow-Ready Solution. If it lives in your own software, connect that software to an IMDA-accredited Access Point. The IRAS guide describes exactly this split.
InvoiceNow-Ready Solution Providers build accounting or finance software with InvoiceNow features and connectivity built in; the guide suggests small businesses without existing solutions, or with solutions already on IMDA's list, approach them. Access Point Providers run the gateways on the network and connect businesses with in-house enterprise solutions; the guide points larger businesses with in-house systems that are not on the list towards them.
A custom InvoiceNow integration sits on the Access Point route. You sign up with an Access Point, receive API credentials and a Peppol ID, and your system sends invoice data to the Access Point's API. The Access Point handles the Peppol network, routing to your customer and transmission to IRAS. Our job is everything on your side of that API.
Where does BtechWaleTech fit in an InvoiceNow integration?
We build the software between your system and your Access Point. We are not an Access Point, not an InvoiceNow-Ready Solution Provider and not on any government list, and we do not transmit anything to IRAS ourselves.
In practice that means reading invoice, credit note and purchase data from your database or ERP, mapping it to the data elements your Access Point's API expects, validating it before sending, calling the API, handling responses and rejections, storing message identifiers against each invoice and producing reconciliation reports. We also help you evaluate what different Access Points' APIs require, so you can compare them on technical fit as well as price.
What we leave to others: the choice of Access Point and its contract (yours), the Peppol network itself (the Access Point's), and every tax decision, from GST category codes to which phase applies (your accountant's). Keeping those lines clear is what makes InvoiceNow integration by an outside team work.
How does the Peppol four-corner model work in InvoiceNow?
The supplier's system (corner 1) sends the invoice to the supplier's Access Point (corner 2), which routes it across the network to the customer's Access Point (corner 3), which delivers it into the customer's system (corner 4). Supplier and customer can use different software and different Access Points and still exchange invoices.
To find the recipient, the supplier's side looks them up via their Peppol ID in the SG Peppol Directory. The IRAS guide notes that Access Points and solution providers help businesses register a Peppol ID and publish their details so they can be found.
For the GST requirement, IRAS is itself connected to the network. When a Peppol invoice travels from supplier to customer, a copy of the invoice data goes to IRAS automatically; the guide calls this the Peppol submission method. Invoices issued outside the network, such as PDF invoices to individuals, and purchase invoices recorded in your system are sent separately under the solution-extracted method. A custom InvoiceNow integration usually has to support both.
How do you map custom invoice data for InvoiceNow integration?
Field by field, starting from a real sample of your invoices and working towards the PINT-SG specification, which the IRAS guide describes as the base data format for the GST InvoiceNow Requirement. Mapping is where most of the effort in an InvoiceNow integration goes, and where most errors are prevented.
We build a mapping sheet with three columns: the required data element, where it lives in your system, and any transformation. Some are simple, like invoice number and date. Others need decisions: how your internal tax codes translate to IRAS's GST category codes, how line-level discounts are represented, how you record customer UENs, and how credit notes reference the original invoice.
Your finance team reviews the sheet before any code is written. Gaps usually surface here: customers stored without UENs, tax codes that mix two treatments, or invoices edited after issue. Fixing those in the source system is better than papering over them in the connector.
- Supplier and customer identifiers, including UEN and Peppol ID.
- Invoice number, issue date and, for credit notes, the referenced invoice.
- Line items with quantities, unit prices, discounts and line totals.
- GST category code per line or subtotal, mapped from your tax codes.
- Totals before and after tax, currency and any rounding.
- Payment terms and due date where your customers need them.
How should validation and errors be handled in an InvoiceNow connector?
Validate before sending, treat every rejection as a work item for a named person, and design retries so the same invoice can never be sent twice. A connector that silently drops errors is worse than none, because you only find the gap at GST return time.
Before sending, our connectors check mandatory fields, totals that add up, valid category codes and correct identifier formats. Access Points apply their own validation against the Peppol rules and return errors; we store each response against the invoice, show rejected items on a dashboard, and alert your team.
Idempotency matters. Network timeouts happen, and a naive retry can create a duplicate. We keep a unique message reference for each document and check it before any resend. Invoices corrected after rejection keep a clear history, so auditors can see what changed and why.
When must invoice data be sent to IRAS?
By the earlier of the date the relevant GST return is filed and that return's filing due date, according to the IRAS guide. The relevant return is the one covering the period in which the transaction date falls.
Peppol invoices generally reach IRAS in real time or near real time as they are delivered to the customer. Solution-extracted data, such as PDF invoices to individuals and purchase records, is sent regularly, for example daily or weekly, depending on how the solution is configured.
For InvoiceNow integration design, that suggests two flows: event-driven sending when an invoice is issued to a customer on the network, and a scheduled batch for everything else. We add a pre-filing report so your finance team can confirm, before submitting the GST return, that every transaction for the period has been transmitted and accepted.
How does InvoiceNow integration work for an online store?
The store usually passes orders to accounting software, which handles InvoiceNow; the store's job is to capture the right data. If the store itself issues the invoices, it needs a connector like any other custom system.
For business buyers, that means asking for the company name, UEN and billing address at checkout or account creation, and storing them against the order. For consumers, the IRAS guide says individuals trading under their personal name are recorded with “NA” for customer UEN, name and address, and point-of-sale and simplified tax invoice transactions have their own treatment. Which applies to your online sales is a question for your accountant.
Refunds and returns need attention: a credit note must reference the original invoice and flow through the same route. Our ecommerce design guide covers store builds, and the QR payment integration guide covers how customers pay.
How do you integrate an in-house ERP with InvoiceNow?
Usually with a small middleware service beside the ERP, rather than changes deep inside it. The service reads posted invoices and purchase records, maps them, calls the Access Point's API and writes the result back to the ERP as a status field.
This keeps the ERP stable, which matters when it is old, heavily customised or maintained by someone else. The middleware can read from database views, export files or the ERP's own API, whichever is safest. It runs in your infrastructure or cloud account, so invoice data never passes through systems you do not control.
For groups with several entities, each with its own UEN and GST registration, the middleware routes documents under the correct identifiers and keeps separate logs. The IRAS guide notes that for system architects and developers, technical documents sit on the APEX portal and in IMDA's InvoiceNow Technical Playbook; your Access Point's API documentation adds its own details.
How is an InvoiceNow integration tested before going live?
In the Access Point's test environment first, with a set of real-looking invoices that cover every document type and tax scenario you use; then with a small, controlled start in production.
- Standard invoice with several lines and mixed GST category codes.
- Credit note referencing an earlier invoice, full and partial.
- Debit note and invoice with discounts or rounding.
- Customer with a UEN, a foreign customer without one, and an individual.
- Purchase record from a supplier outside the network.
- Deliberately broken invoice to prove rejections are caught and alerted.
- Network timeout during sending, to prove no duplicate is created.
After testing, we reconcile: the totals transmitted for a trial period should match what your accounting shows for that period. Only then do we switch on production sending, often for one entity or document type first. Your finance team signs off each stage.
What changes for your finance team after InvoiceNow integration?
Less typing and chasing, more exception handling. Once the connector is live, routine invoices leave your system as data, supplier e-invoices arrive the same way, and your team's work shifts to reviewing the few documents that fail validation or need a decision.
Month-end looks different too. Instead of assembling GST figures from spreadsheets and hoping they match, the finance lead opens the reconciliation view, confirms every document for the period shows as accepted, investigates anything pending, and files. The IRAS guide lists streamlined processes, fewer errors and better cash-flow management among the benefits of InvoiceNow-Ready solutions, since structured invoices can be processed and paid faster by customers.
Some habits need to change for InvoiceNow integration to work well. Invoices should not be edited after issue; corrections go through credit or debit notes. Customer records need a UEN before the first invoice, not after. New tax scenarios, such as a first export sale, should be raised with the accountant and added to the mapping before they occur. We write a one-page operating note covering these points and walk your team through it at handover, so the connector stays reliable long after we finish.
How much does InvoiceNow integration cost?
With BtechWaleTech, a custom InvoiceNow integration connector starts at US$900. Access Point fees are separate and paid to the provider you choose. The biggest cost factors are the number of source systems, document types and the quality of your existing data.
Quotes for this work vary widely, because two projects with the same name can differ tenfold in effort. Sending clean invoices from one modern system is modest. Extracting invoices and purchases from an old ERP with inconsistent tax codes, across three entities, with two-way status updates, is a much larger build.
Before comparing prices, compare scope: does the quote include purchase records, credit notes, reconciliation, alerts and maintenance, or only outgoing invoices? Also compare against switching to an InvoiceNow-Ready accounting package, which is sometimes the cheaper answer. We include that comparison in our written recommendation.
InvoiceNow integration with a team in India: access, data and hours
A connector project needs access to your invoicing data and an Access Point sandbox, and both can be arranged safely for a remote team. India is two and a half hours behind Singapore, so a 10 am SGT review with your finance manager is 7:30 am for us, and we remain online well into your afternoon.
We develop against test data and the Access Point's sandbox. The production connector runs in your cloud account or on your servers; API credentials for the Access Point are stored there, not on our machines. Where we need to see real invoices to fix a mapping issue, we agree it with you first. Quotes are in USD, invoices come from India, and payment is by Wise or bank wire.
The first two weeks usually include a walkthrough of how invoices are created today, a sample export of fifty to a hundred invoices and purchases, the first draft of the mapping sheet for your finance team, and sandbox credentials from your Access Point so a first test document can be sent. For wider context on working this way, see outsourcing development to India.
Example: a trading company registering for GST voluntarily
Suppose a hypothetical trading company runs a custom order and invoicing platform built years ago, and plans to register for GST voluntarily in 2026. Under the IRAS phases, new voluntary registrants from 1 April 2026 must meet the InvoiceNow requirement, so the platform must be ready when registration takes effect. This scenario is illustrative only.
The InvoiceNow integration plan would start with a mapping workshop and a decision on an Access Point. A middleware service would read issued invoices and credit notes from the platform, map them to PINT-SG with GST category codes agreed with the accountant, and send them through the Access Point's API. Purchase records entered in the platform would go in a daily batch. A dashboard would show accepted and rejected documents, and a pre-filing report would compare transmitted totals with the platform's GST figures.
A build like this would start from US$900 and typically take eight to ten weeks, including sandbox testing and a trial period. If the company's volumes were low and its needs simple, we would first ask whether an InvoiceNow-Ready accounting package could replace the invoicing module altogether.
InvoiceNow integration checklist and red flags
Use this before signing off an InvoiceNow integration project, whoever builds it.
- Your accountant has confirmed your implementation phase and date.
- You have chosen and contracted an IMDA-accredited Access Point.
- The mapping sheet covers invoices, credit notes, debit notes and purchases.
- Internal tax codes map one-to-one to GST category codes.
- Customer UEN, name and address are captured where required.
- Rejections alert a named person and cannot be silently lost.
- Retries cannot create duplicate documents.
- A pre-filing reconciliation report exists and has been tested.
- Credentials and logs live in your infrastructure.
- Red flag: a developer claiming to be an Access Point or IRAS-approved when they are not.
- Red flag: a quote that covers only outgoing invoices and ignores purchases.