Build an InvoiceNow (Peppol SG) E-Invoice into PINT SG UBL XML

Skill: Convert invoice data into a Peppol PINT SG UBL Invoice for InvoiceNow

Region: Singapore Category: E-invoicing — InvoiceNow (IMDA Peppol, IRAS GST) Does: Takes invoice data (PDF/CSV/JSON/pasted) and produces a Peppol PINT SG UBL 2.1 Invoice transmitted over the InvoiceNow (Peppol) network, with the UEN-based Peppol participant ID, Singapore GST category codes, and 9% GST breakdown. Standard: Peppol PINT Singapore (SG Billing) — UBL 2.1 Invoice, CustomizationID urn:peppol:pint:billing-1@sg-1

The AI produces the XML business document only. The four-corner delivery, sender/receiver access-point routing, and the IRAS GST InvoiceNow transmission (the additional fifth-corner feed to IRAS for GST-registered businesses) are handled by your Access Point / solution provider. Validate against the current PINT SG rules (BIS/Schematron) before sending — the PINT specification and IRAS transmission scope phase in over 2025–2026.

When this applies

• A Singapore supplier sends a structured e-invoice to a customer over the InvoiceNow (Peppol) network operated under IMDA.
• GST-registered businesses additionally transmit invoice data to IRAS through InvoiceNow under the phased timeline (newly incorporated/voluntary registrants from 2025; broader GST-registered population from 2026 — verify your trigger date).
• Not for pure paper/PDF invoicing, and not for the GST F5 return itself (that is a separate periodic summary — see tax/build-gst-f5-return.md).

Conversion procedure

1. Read the source. Accept a PDF text layer, CSV, JSON, or pasted invoice. Identify supplier, customer, line items, GST treatment, and totals.
2. Extract fields. Capture both parties' UEN, the invoice number and issue date, currency (SGD unless stated), each line's quantity/unit price/GST category, and the document totals. If the supplier or customer UEN, the invoice number, or any line amount is missing, stop and ask — never invent a UEN.
3. Normalize. Dates to YYYY-MM-DD. Amounts to a dot decimal, 2 places. Map the GST treatment of every line to a single-letter UBL tax category code (see code tables). Build each Peppol Endpoint ID as scheme 0195 (SG:UEN) + the UEN value.
4. Compute. Per line: LineExtensionAmount = Quantity × PriceAmount (2 dp). Group lines by tax category/rate into TaxSubtotals. TaxAmount = TaxableAmount × rate (2 dp). Reconcile LegalMonetaryTotal.
5. Emit the Invoice using the document structure and worked example below as the template.
6. Validate against the checklist and the current PINT SG Schematron.

Source → PINT SG UBL field map

Every required output element appears above. Repeat cac:InvoiceLine per line and cac:TaxSubtotal per distinct category/rate.

Document structure

Invoice
├── cbc:CustomizationID            (urn:peppol:pint:billing-1@sg-1)
├── cbc:ProfileID                  (urn:peppol:bis:billing)
├── cbc:ID                         (invoice number)
├── cbc:IssueDate                  (YYYY-MM-DD)
├── cbc:InvoiceTypeCode            (380)
├── cbc:DocumentCurrencyCode       (SGD)
├── cac:AccountingSupplierParty
│   └── cac:Party
│       ├── cbc:EndpointID schemeID="0195"   (supplier UEN)
│       ├── cac:PartyTaxScheme/cbc:CompanyID  (GST registration / UEN)
│       └── cac:PartyLegalEntity/cbc:RegistrationName
├── cac:AccountingCustomerParty
│   └── cac:Party
│       ├── cbc:EndpointID schemeID="0195"   (customer UEN)
│       └── cac:PartyLegalEntity/cbc:RegistrationName
├── cac:TaxTotal
│   ├── cbc:TaxAmount
│   └── cac:TaxSubtotal ...        (one per category/rate)
├── cac:LegalMonetaryTotal
│   ├── cbc:LineExtensionAmount
│   ├── cbc:TaxExclusiveAmount
│   ├── cbc:TaxInclusiveAmount
│   └── cbc:PayableAmount
└── cac:InvoiceLine ...            (one per line)

Code tables

GST category (cac:ClassifiedTaxCategory/cbc:ID, UNCL5305)

cbc:InvoiceTypeCode (UNCL1001, selected)

schemeID for SG participant identifiers

Calculation rules

• Line extension = Quantity × PriceAmount, rounded to 2 dp.
• TaxableAmount per category = Σ of line extensions in that category.
• TaxAmount per category = TaxableAmount × rate (e.g. 100.00 × 9% = 9.00), 2 dp. ZR/ES/OS → 0.00.
• cbc:TaxExclusiveAmount = Σ line extensions; TaxInclusiveAmount = TaxExclusive + total tax; PayableAmount = TaxInclusive − any prepaid.
• Amounts carry the currencyID attribute (SGD). Recompute every total; flag any mismatch with the source.

Worked example (end-to-end)

Input — pasted invoice

Supplier: Acme Tech Pte Ltd  UEN 201912345A (GST registered)
Customer: Buyer Holdings Pte Ltd  UEN 200612345B
Invoice INV-2026-0042, dated 14 Jun 2026, SGD
Line 1: Consulting services, 10 hrs @ 100.00  — standard-rated 9%

After extraction + normalization (intermediate)

{
  "id": "INV-2026-0042", "issueDate": "2026-06-14", "currency": "SGD",
  "supplier": {"uen": "201912345A", "name": "Acme Tech Pte Ltd"},
  "customer": {"uen": "200612345B", "name": "Buyer Holdings Pte Ltd"},
  "lines": [{"desc": "Consulting services", "qty": 10, "price": 100.00, "cat": "SR", "rate": 9, "net": 1000.00}]
}

Output — PINT SG UBL Invoice

<?xml version="1.0" encoding="UTF-8"?>
<Invoice xmlns="urn:oasis:names:specification:ubl:schema:xsd:Invoice-2"
         xmlns:cac="urn:oasis:names:specification:ubl:schema:xsd:CommonAggregateComponents-2"
         xmlns:cbc="urn:oasis:names:specification:ubl:schema:xsd:CommonBasicComponents-2">
  <cbc:CustomizationID>urn:peppol:pint:billing-1@sg-1</cbc:CustomizationID>
  <cbc:ProfileID>urn:peppol:bis:billing</cbc:ProfileID>
  <cbc:ID>INV-2026-0042</cbc:ID>
  <cbc:IssueDate>2026-06-14</cbc:IssueDate>
  <cbc:InvoiceTypeCode>380</cbc:InvoiceTypeCode>
  <cbc:DocumentCurrencyCode>SGD</cbc:DocumentCurrencyCode>
  <cac:AccountingSupplierParty>
    <cac:Party>
      <cbc:EndpointID schemeID="0195">201912345A</cbc:EndpointID>
      <cac:PartyTaxScheme>
        <cbc:CompanyID>201912345A</cbc:CompanyID>
        <cac:TaxScheme><cbc:ID>GST</cbc:ID></cac:TaxScheme>
      </cac:PartyTaxScheme>
      <cac:PartyLegalEntity>
        <cbc:RegistrationName>Acme Tech Pte Ltd</cbc:RegistrationName>
        <cbc:CompanyID schemeID="0195">201912345A</cbc:CompanyID>
      </cac:PartyLegalEntity>
    </cac:Party>
  </cac:AccountingSupplierParty>
  <cac:AccountingCustomerParty>
    <cac:Party>
      <cbc:EndpointID schemeID="0195">200612345B</cbc:EndpointID>
      <cac:PartyLegalEntity>
        <cbc:RegistrationName>Buyer Holdings Pte Ltd</cbc:RegistrationName>
        <cbc:CompanyID schemeID="0195">200612345B</cbc:CompanyID>
      </cac:PartyLegalEntity>
    </cac:Party>
  </cac:AccountingCustomerParty>
  <cac:TaxTotal>
    <cbc:TaxAmount currencyID="SGD">90.00</cbc:TaxAmount>
    <cac:TaxSubtotal>
      <cbc:TaxableAmount currencyID="SGD">1000.00</cbc:TaxableAmount>
      <cbc:TaxAmount currencyID="SGD">90.00</cbc:TaxAmount>
      <cac:TaxCategory>
        <cbc:ID>SR</cbc:ID>
        <cbc:Percent>9</cbc:Percent>
        <cac:TaxScheme><cbc:ID>GST</cbc:ID></cac:TaxScheme>
      </cac:TaxCategory>
    </cac:TaxSubtotal>
  </cac:TaxTotal>
  <cac:LegalMonetaryTotal>
    <cbc:LineExtensionAmount currencyID="SGD">1000.00</cbc:LineExtensionAmount>
    <cbc:TaxExclusiveAmount currencyID="SGD">1000.00</cbc:TaxExclusiveAmount>
    <cbc:TaxInclusiveAmount currencyID="SGD">1090.00</cbc:TaxInclusiveAmount>
    <cbc:PayableAmount currencyID="SGD">1090.00</cbc:PayableAmount>
  </cac:LegalMonetaryTotal>
  <cac:InvoiceLine>
    <cbc:ID>1</cbc:ID>
    <cbc:InvoicedQuantity unitCode="HUR">10</cbc:InvoicedQuantity>
    <cbc:LineExtensionAmount currencyID="SGD">1000.00</cbc:LineExtensionAmount>
    <cac:Item>
      <cbc:Name>Consulting services</cbc:Name>
      <cac:ClassifiedTaxCategory>
        <cbc:ID>SR</cbc:ID>
        <cbc:Percent>9</cbc:Percent>
        <cac:TaxScheme><cbc:ID>GST</cbc:ID></cac:TaxScheme>
      </cac:ClassifiedTaxCategory>
    </cac:Item>
    <cac:Price><cbc:PriceAmount currencyID="SGD">100.00</cbc:PriceAmount></cac:Price>
  </cac:InvoiceLine>
</Invoice>

Normalisations shown: 14 Jun 2026 → 2026-06-14; UEN wrapped as schemeID="0195"; line net recomputed 10 × 100.00 = 1000.00; GST recomputed 1000.00 × 9% = 90.00; TaxInclusiveAmount = 1000.00 + 90.00 = 1090.00.

Validation checklist

• All required fields extracted; AI asked about any missing UEN, invoice number, date, or amount (nothing invented)
• cbc:CustomizationID = urn:peppol:pint:billing-1@sg-1; cbc:ProfileID set
• Both parties carry EndpointID schemeID="0195" with a valid UEN
• Each line has a ClassifiedTaxCategory (SR/ZR/ES/OS) with the correct Percent
• One cac:TaxSubtotal per category; TaxAmount = TaxableAmount × rate (2 dp)
• LegalMonetaryTotal reconciles: TaxExclusive = Σ lines; TaxInclusive = TaxExclusive + total tax
• All amounts carry currencyID="SGD", 2 dp; dates YYYY-MM-DD
• Document validates against the current PINT SG Schematron before transmission

Last updated: 2026-06-13 — verify the active PINT SG specification version, Peppol BIS/Schematron rules, GST rate, and the IRAS GST InvoiceNow transmission timeline before use.