If your business is newly GST-registered in Singapore, you now need to transmit invoice data to IRAS through InvoiceNow, not as a future obligation, but as a condition of registration today. This guide walks you through every step, from picking an accredited provider to confirming your first live e-invoice reached both your customer and IRAS.
At a Glance
| Field | Detail
|
|---|---|
| Outcome | Peppol ID registered; first e-invoice sent to customer and IRAS |
| Time required | Verify current timeline with IRAS |
| Difficulty | Moderate, three setup steps, then routine |
| Prerequisites | UEN, Corppass admin access, IMDA-accredited provider |
| Cost | S$0 via FOC package (until 31 March 2027) |
What You’ll Achieve
Once you complete these steps, your business will hold a UEN-based Peppol ID, appear in the SG Peppol Directory, and be able to send PINT-SG structured e-invoices to trading partners and IRAS simultaneously. This is the outcome required to satisfy Singapore’s GST InvoiceNow mandate.
Who needs this:
- New voluntary GST registrants from 1 April 2026, InvoiceNow compliance is a condition of approval
- Newly incorporated companies that voluntarily registered for GST from 1 November 2025
- Existing GST-registered businesses under the phased mandatory rollout (1 April 2028–2031, by revenue band), confirm your applicable deadline at the IRAS GST InvoiceNow page/gst-invoicenow-requirement)
- Businesses registered under Reverse Charge or OVR regimes are excluded
Before You Start
Before you touch any software, four things must be in place. A missing UEN means no Peppol ID; no Corppass means the registration can’t be authorised. Check all four now so nothing stalls you mid-process.
Prerequisites checklist:
- Valid UEN, your Peppol ID will be 0195:YourUEN. If you don’t have a UEN, register with ACRA first.
- Corppass admin access, the KYC authorisation email goes to your Corppass administrator. Apply at corppass.gov.sg if not set up.
- IMDA-accredited provider, either an InvoiceNow-Ready Solution Provider (IRSP) for off-the-shelf accounting software, or an Access Point Provider (AP) for in-house ERP systems. Check the current list at imda.gov.sg/invoicenow.
- GST registration number, needed to enable IRAS submission in Step 3. For mandatory participants, confirm your GST Reg No. with IRAS before configuring the software toggle.
Step-by-Step: How to Send Your First InvoiceNow Invoice
The full journey has three setup steps, selecting a provider, obtaining your Peppol ID, and enabling IRAS submission, followed by sending your first invoice. Off-the-shelf software users follow the IRSP path; businesses with custom ERP systems follow the AP path. Steps 2 and 3 are identical for both.
Step 1: Select an IMDA-accredited provider
Open the IMDA IRSP list at imda.gov.sg/invoicenow and confirm your software appears on it. If it does, ask the provider to activate InvoiceNow. If it doesn’t, either switch to an accredited solution or engage an AP to integrate your existing system.
Why it matters: Only accredited providers can register your Peppol ID and route invoice data to IRAS. A non-accredited platform cannot satisfy the mandate regardless of what it claims.
Pitfall: Don’t pay for software before verifying accreditation. If you’re applying for PSG grant support, submit the grant application before making payment, paying first disqualifies the claim.
Step 2: Register in the SG Peppol Directory and obtain your Peppol ID
Ask your IRSP or AP to initiate registration. You’ll receive a Corppass authorisation email from SGNIC Support at donotreply@peppolsmp.sg. Log in via Corppass, select your company UEN, and authorise the registration.
Why it matters: Your Peppol ID (0195:YourUEN) is your permanent digital address on the network, nothing can be sent or received without it.
Pitfall: Check spam folders immediately after your provider initiates registration. The wrong Corppass user attempting authorisation is the most common stall. Per IMDA’s service requirements, your provider must complete registration within three working days of your request.
Step 3: Enable the GST InvoiceNow submission feature
Log into your accounting software and find the InvoiceNow or GST submission settings. Toggle “Transmit invoice data to IRAS” ON, enter your GST registration number, and save. Then send a test invoice and confirm the dashboard shows both customer delivery and IRAS transmission as successful.
Why it matters: Per IRAS requirements/gst-invoicenow-requirement), only structured PINT-SG XML invoices delivered through the Peppol network satisfy the mandate, PDF attachments and emails do not count.
Pitfall: Activating Peppol B2B transmission to customers is a separate toggle from IRAS submission. Confirm both are ON before going live.
Step 4: Send your first invoice
Look up your customer’s Peppol ID in the SG Peppol Directory using their UEN, format: 0195:CustomerUEN. Create the invoice in your software, populate all mandatory fields, and select “Send via InvoiceNow”. Your software generates PINT-SG XML and transmits it to both the customer and IRAS simultaneously. Confirm delivery in the dashboard.
Pitfall: If the customer isn’t registered on InvoiceNow, transmission will fail. Send a PDF invoice by email as a fallback until they register.
Variations & Edge Cases
- Existing software not on the IMDA list, engage an AP to integrate it (enterprise path), or migrate to an accredited solution. Affects Step 1.
- Non-GST-registered business using InvoiceNow voluntarily, registration is identical, but skip the IRAS submission toggle in Step 3. You exchange B2B e-invoices on the 4-corner Peppol model only.
- Invoicing government agencies, about 50% of government vendors are now on InvoiceNow. IMDA has centrally registered Peppol IDs for all agencies; look up the agency’s ID in the directory before Step 4.
- Foreign company with a Singapore UEN, Corppass KYC is not required. Your AP registers the Peppol ID using a Letter of Authorisation signed by a company director instead.
Troubleshooting
| Problem | Likely cause | Fix
|
|---|---|---|
| “GST registration number invalid on invoice date” | GST status was not active on that date | Verify GST status with IRAS; correct date or contact IRAS |
| Corppass authorisation email not received | Spam folder, wrong email, SGNIC emails blocked | Check spam; ask IRSP to resend; whitelist donotreply@peppolsmp.sg |
| “Mandatory data element missing” rejection | UEN, GST number, or line GST code not populated | Check all mandatory fields; validate against IRAS element list |
| Peppol ID already registered with another provider | Previous provider didn’t de-register the UEN | Contact previous provider to release Peppol ID from Singapore SMP |
| “Recipient not found on Peppol network” | Customer not registered, or wrong ID format | Search directory by 0195:CustomerUEN; send PDF fallback if unregistered |
Common Mistakes
- Buying software before checking the IMDA list, you can end up locked into a non-compliant platform. Always verify accreditation first; apply for PSG before paying.
- Activating Peppol B2B but not the IRAS submission toggle, customer delivery succeeds but IRAS receives nothing, violating the GST InvoiceNow Requirement. Confirm both features are ON and test before going live.
- Entering the customer’s UEN alone instead of 0195:UEN, transmission fails silently. Use the full Peppol ID format every time; verify in the invoice preview before sending.
- Skipping validation testing before going live, live rejections disrupt GST reporting. Use IMDA’s Validex tool to validate test invoices and confirm IRAS acceptance before processing real transactions.
Worked Example
Apex Engineering Pte Ltd (UEN 202301234A) voluntarily registers for GST in May 2026 to claim input tax on imported machinery. Starting from non-accredited software, Apex completes full onboarding and sends its first live GST invoice to BuildCo Pte Ltd. Here’s how each step played out.
Week 1, Step 1: Apex reviews the IMDA IRSP list and selects a FOC accounting package, avoiding subscription costs during the transition period. The CFO migrates the chart of accounts and customer/supplier master data. Cost: S$0.
Week 2, Step 2: The IRSP initiates registration. The CFO receives the SGNIC email at donotreply@peppolsmp.sg, logs in via Corppass, and selects UEN 202301234A. Peppol ID 0195:202301234A is confirmed in the SG Peppol Directory within three working days, in line with IMDA’s service requirement.
Week 3, Step 3: IRAS issues Apex’s GST Reg No. The CFO enters it in the InvoiceNow settings and toggles IRAS submission ON. A test invoice transmits successfully, the dashboard confirms delivery to the customer Peppol ID and IRAS transmission success.
Week 4, First live invoice: Apex invoices BuildCo (Peppol ID 0195:200912345B) for structural fabrication services. The software auto-populates all mandatory IRAS fields, supplier UEN, supplier GST number, customer UEN, customer GST number, GST category code SR, and GST amount, then generates PINT-SG XML and transmits to both BuildCo and IRAS simultaneously. BuildCo’s system auto-posts the invoice to accounts payable. IRAS records the output tax for Apex’s next GST return.
Total cost: S$0 (FOC package until 31 March 2027; Apex is also eligible for the S$1,000 Transition Grant).
Where Rockbell Fits
Rockbell is an IMDA-accredited InvoiceNow-Ready Solution Provider (IRSP). It helps GST-registered businesses connect to the Peppol network through a range of software and services.
Accounting software with InvoiceNow: Million, AutoCount, UBS, Xero, and Jaz, activate InvoiceNow within your current platform or migrate to a compliant solution. Rockbell also offers Payroll & HR Management (Million Payroll, HR Suite) and Point-of-Sale Systems (Million POS, Popcorn POS, AutoCount POS, AutoCount OneSales POS Cloud) that connect to InvoiceNow workflows.
Professional services include:
- Setup, Peppol ID registration, Corppass KYC support, IRAS submission configuration
- Training, invoice creation, mandatory data elements, directory lookup, and validation testing
- Data Migration, customer/supplier master data, chart of accounts, and historical invoices
- Customisation, API integration for in-house ERP systems and multi-entity GST reporting
- Grant Facilitation, PSG application support and Transition Grant claim assistance
Rockbell holds credentials relevant to InvoiceNow. Verify its current status on the official IMDA IRSP directory at imda.gov.sg/invoicenow before booking.
Frequently Asked Questions
How do I find my customer’s Peppol ID?
Search the SG Peppol Directory by your customer’s UEN using the format 0195:CustomerUEN. If they don’t appear, they aren’t registered, send a PDF invoice by email until they onboard.
What happens if I send an invoice to IRAS with an incorrect GST registration number?
IRAS validates the GST Reg No. against the invoice date and rejects the submission automatically. You’ll need to correct the number and retransmit; contact IRAS if the registration status itself is in question.
Can I use InvoiceNow if my accounting software is not on the IMDA accredited list?
Yes, engage an IMDA-accredited Access Point Provider to integrate your existing system with the Peppol network. Alternatively, migrate to an accredited InvoiceNow-Ready solution.
Do I need to register for InvoiceNow if I am not GST-registered?
No, it’s not mandatory. Some IRSPs offer free solutions for non-GST-registered businesses that want to exchange B2B e-invoices with trading partners on the 4-corner Peppol model.
What is the difference between Peppol e-invoicing and GST InvoiceNow submission to IRAS?
Peppol e-invoicing (4-corner model) delivers structured invoices between you and your trading partner. GST InvoiceNow submission adds a fifth corner, IRAS receives a copy of the invoice data simultaneously, satisfying the tax reporting mandate.