How SwissDIGIN extends PEPPOL BIS Billing 3.0 for Switzerland

PEPPOL BIS Billing 3.0 is the pan-European invoice standard. It works across 35+ countries without modification. But Switzerland has requirements that are not in the base standard — a different company identifier, different VAT rules, and payment references tied to the QR-bill infrastructure. SwissDIGIN is the Swiss standards initiative that defines how PEPPOL BIS Billing 3.0 should be used in Switzerland, including the specific extensions and restrictions that make Swiss e-invoices conformant with both European and local requirements.

This post covers what SwissDIGIN actually adds and why each change exists.

What SwissDIGIN is

SwissDIGIN (Swiss Digital Invoice) is a community-driven specification maintained by a working group that includes Swiss banks, ERP vendors, and public sector organisations. The specification describes a subset and extension of PEPPOL BIS Billing 3.0 that is valid for Swiss domestic and cross-border use.

The SwissDIGIN specification sits alongside — not instead of — the PEPPOL BIS standard. A SwissDIGIN-conformant invoice is also a valid PEPPOL BIS 3.0 invoice. The extensions use mechanisms already defined in PEPPOL BIS (such as optional fields and customisation IDs) rather than breaking the format. This means a PEPPOL-capable buyer in Germany can receive a Swiss SwissDIGIN invoice and process it without modification, even if they do not know anything about SwissDIGIN specifically.

The Swiss company identifier (UID)

In most European countries, PEPPOL invoices carry a VAT number as the party identifier. Switzerland uses the UID (Unternehmens-Identifikationsnummer) instead. The UID format is CHE-123.456.789 — a nine-digit number prefixed with CHE and formatted with dots.

In PEPPOL BIS XML, party identifiers sit in <cac:PartyIdentification> or <cac:PartyTaxScheme>. SwissDIGIN specifies:

The scheme identifier for UID in the PEPPOL party identification is CHE
VAT-registered parties use CHE-123.456.789 MWST as the tax registration number in <cac:CompanyID> within the VAT scheme block
Non-VAT-registered parties (small businesses below the CHF 100,000 revenue threshold) should omit the tax scheme block entirely rather than leaving it blank

<cac:PartyTaxScheme>
  <cbc:CompanyID>CHE-116.281.710 MWST</cbc:CompanyID>
  <cac:TaxScheme>
    <cbc:ID>VAT</cbc:ID>
  </cac:TaxScheme>
</cac:PartyTaxScheme>

The MWST suffix (Mehrwertsteuer, German for VAT) is the Swiss convention. The equivalent in French-speaking cantons is TVA, but for the XML value, MWST is the standard used across all SwissDIGIN invoices regardless of the invoice language.

Currency and amounts

Switzerland uses the Swiss franc (CHF), which is outside the Euro zone. The base PEPPOL BIS standard allows any ISO 4217 currency, so this is not an extension — but SwissDIGIN documents confirm that CHF is the primary currency for domestic Swiss invoices.

For invoices in EUR (common in cross-border trade), the currency code changes to EUR and no other structural changes are required. Swiss banks can receive payments in EUR and the PEPPOL infrastructure carries EUR-denominated invoices without issue.

One point specific to Switzerland: rounding rules for CHF. Swiss francs are rounded to 0.05 because Swiss coins do not include 1 or 2 centime denominations. In practice, invoice totals are stated to two decimal places in the XML (as required by PEPPOL BIS), and any display rounding to 0.05 is a presentation concern, not a document concern. If a transaction results in an amount like CHF 123.47, the XML carries 123.47 even though the payer's bank may execute the payment as CHF 123.45.

Payment means and the QR reference

The base PEPPOL BIS standard supports several payment means codes (defined in the UNCL4461 code list). For Swiss domestic payments, SwissDIGIN uses payment means code 58 (SEPA credit transfer — reused in Switzerland for IBAN-based transfers) or 30 for credit transfers where specific bank details are provided.

More significantly, SwissDIGIN defines how to carry the QR reference (QR-Referenz) and QR-IBAN from a QR-bill inside a PEPPOL invoice. The relevant XML block is in <cac:PaymentMeans>:

<cac:PaymentMeans>
  <cbc:PaymentMeansCode>58</cbc:PaymentMeansCode>
  <cbc:PaymentID>210000000003139471430009017</cbc:PaymentID>
  <cac:PayeeFinancialAccount>
    <cbc:ID>CH4431999123000889012</cbc:ID>
    <cbc:Name>Muster AG</cbc:Name>
  </cac:PayeeFinancialAccount>
</cac:PaymentMeans>

The <cbc:PaymentID> carries the 27-digit QR reference. The <cbc:ID> in PayeeFinancialAccount is the QR-IBAN (without spaces). When a buyer's ERP processes this invoice, it can extract both the QR-IBAN and the QR reference and populate the payment instruction directly, without any manual data entry. This is the structural bridge between PEPPOL e-invoicing and the QR-bill payment infrastructure.

For invoices using an ISO creditor reference (SCOR) instead of a QR reference, the <cbc:PaymentID> carries the SCOR reference in the format RF18539007547034.

VAT rates and the Swiss-specific 3.8% rate

The base PEPPOL BIS standard includes the EN 16931 tax model, which supports multiple VAT rates on a single invoice. Switzerland has three VAT rates:

Standard rate: 8.1%
Reduced rate: 2.6% (food, books, medicines, newspapers)
Special rate: 3.8% (hotel and accommodation services)

The 3.8% hospitality rate is unusual in the European context and not always handled well by non-Swiss ERP systems. SwissDIGIN confirms that all three rates are valid in <cac:TaxCategory> and that the correct <cbc:Percent> values are 8.1, 2.6, and 3.8. Tax category code S applies to all three — there is no separate category code for the reduced or special rates in the Swiss context. The rate value itself distinguishes them.

The SwissDIGIN customisation ID

PEPPOL documents carry a CustomizationID that identifies the specification the invoice conforms to. For standard PEPPOL BIS Billing 3.0, this is:

urn:cen.eu:en16931:2017#compliant#urn:fdc:peppol.eu:2017:poacc:billing:3.0

SwissDIGIN invoices that use the Swiss extensions carry an additional layer:

urn:cen.eu:en16931:2017#compliant#urn:fdc:peppol.eu:2017:poacc:billing:3.0#conformant#urn:fdc:swissdigin.ch:2018:invoicing:1.0

This extended ID tells a receiving system that the invoice follows the SwissDIGIN profile and may carry Swiss-specific fields. Receivers that only understand base PEPPOL BIS can still process the invoice — the customisation ID is metadata, not a structural change.

Schematron rules

The SwissDIGIN specification includes its own Schematron rule set that validates Swiss-specific constraints on top of the base PEPPOL BIS Schematron. The Swiss rules check things like:

UID format validity (must match CHE-\d{3}\.\d{3}\.\d{3})
MWST suffix present when a VAT-registered Swiss supplier is identified
QR-IBAN format when a QR reference is present
Consistent use of CHF as currency for domestic invoices

You can run the SwissDIGIN Schematron alongside the standard PEPPOL BIS Schematron. The SwissDIGIN validation tool runs both in sequence and reports errors from each separately, so you can see whether a failure is a PEPPOL BIS conformance issue or a Swiss-specific one.

What this means in practice

For a Swiss biller using an ERP that already supports PEPPOL BIS Billing 3.0, moving to SwissDIGIN conformance is usually a configuration exercise rather than a development project. The structural changes are small. The main additions are:

Use the UID (with MWST) as the tax registration number instead of a EU VAT number
Populate <cbc:PaymentID> with the QR reference when applicable
Use the QR-IBAN in PayeeFinancialAccount instead of the standard IBAN
Confirm the customisation ID matches the SwissDIGIN profile

The SwissDIGIN field mapping guide covers the full field-by-field list. For the PEPPOL BIS structure itself, the line-by-line walkthrough of PEPPOL BIS Billing 3.0 is a useful reference alongside the SwissDIGIN specification.