CEN formally approved the revised standard EN 16931-1:2026 on 13 March 2026; NEN published the national version in March 2026. The standard replaces EN 16931-1:2017+A1:2019 and is not backward-compatible. Instances conforming to the new standard use urn:cen.eu:en16931:2026 as Specification identifier (BT-24). Implementation via OpenPeppol follows through BIS Billing 4.0 — expected in production 2027.
This article describes the eight major technical changes, based on Annex A and Table 28 of the standard.
Note: the changes in this article are future-effective. In the current production environment (BIS Billing V3 on EN 16931-1:2017), current rules apply until OpenPeppol publishes an updated specification version.
Change 1: decimal precision is currency-dependent
The biggest impact for processing incoming invoices.
Old (2017): all amounts are rounded to 2 decimal places, regardless of currency.
New (2026): the allowed number of decimal places is determined by the "minor unit" column of ISO 4217 for the currency used.
00JPY, KRW11MRU22EUR, USD, GBP33KWD, BHD44CLF, UYWThis rule applies at line level, document level and totals — for all amount Business Terms in Table 28 (including BT-92, BT-93, BT-99, BT-100, BT-106 to BT-117, BT-131, BT-136, BT-137, BT-141, BT-142, BT-172, BT-179, BT-183).
Exceptions (fixed decimal places regardless of currency)
BT-129Invoiced quantity4BT-146, BT-147, BT-148Item net price, Item price discount, Item gross priceISO 4217 minor unit + 2 extraBT-149Item price base quantity2BT-167VAT accounting currency exchange rate6Percentages (BT-119, BT-94, BT-101, BT-138, BT-143, BT-152, BT-171, BT-182 etc.)VAT rates and discount percentages2Impact eConnect:
- Outbound: invoices are always sent in EUR (minor unit 2) — no change.
- Inbound: invoices may originate from currencies with minor unit up to 4. Processing must handle up to 4 decimal places; for price Business Terms (BT-146/147/148) up to minor unit + 2 extra decimal places.
Change 2: new rounding rules (6.5.14)
- Document totals rounded to the ISO 4217 minor unit of the invoice currency.
- Round on the end result of a calculation business rule — never on intermediate results.
- BT-117 (VAT category tax amount): round at document level, not as the sum of rounded line VAT amounts.
- Rounding method: "half up" away from zero (1.005 becomes 1.01; -1.005 becomes -1.01), decimal (not binary), per IEEE/ISO/IEC 60559:2020.
- Tolerance for multiplication/division (except BT-92, BT-99, BT-131):
Tolerance = min(max(0.001 x [value], 0.01), 1). Not more than 0.1% of the absolute calculated value, minimum 0.01, maximum 1.00.
Change 3: currency and VAT accounting
- R54: invoice currency at document level required, supplemented with VAT accounting/reporting currency (if different) and exchange rates.
- New BT-6: VAT accounting currency code (0..1).
- New BT-167: VAT accounting currency exchange rate (0..1, 6 decimal places).
- BT-111: Invoice total VAT amount in VAT accounting currency — required when BT-6 is present and the accounting currency differs from the invoice currency.
Change 4: structured payment terms, discount and penalty (R71)
New business groups:
BG-33PAYMENT TERMS0..nBT-20 Payment term textBG-35EARLY PAYMENT DISCOUNT0..nBT-170 Discount end date (1..1), BT-171 Discount percentage, BT-172 Discount amountBG-36LATE PAYMENT PENALTY0..nBT-181 Penalty start date (1..1), BT-182 Penalty yearly interest percentage, BT-183 Penalty amountRules:
- With multiple early payment discounts (BG-35), only the highest applicable discount applies; discounts do not accumulate.
- With repeated penalty specifications (BG-36), the last one applies, determined by BT-181.
Change 5: charges on behalf of third parties (R72)
New: BT-179 Charge amount collected on behalf of a third party. Decimal places follow the ISO 4217 minor unit. This amount is not part of the invoice itself, but is included in the amount due including any rounding amount.
Change 6: corrective and preceding invoices
- BT-25: Preceding invoice reference (cardinality 1..1 in correction context).
- BT-26: Preceding invoice issue date (0..1).
- BT-202: Preceding invoice type code (0..1; code from UNTDID 1001 subset, managed on behalf of CEN/TC434).
These fields support linking a final invoice to preceding pre-payment invoices (business rules R11 and R12).
Change 7: other new and changed Business Terms
BT-166Invoice issue timeNew (0..1, Time) — time of invoicingBT-3Invoice type codeUNTDID 1001 subset, managed on behalf of CEN/TC434BT-7 / BT-8VAT point date / VAT point date codeMutually exclusiveBT-10Buyer referenceCardinality 0..n (was single value)BT-15 / BT-16Receiving advice reference / Despatch advice referenceReference to multiple despatch/receiving advices (R9, R10)BT-84Payment account identifierRequired for credit transfer (e.g. IBAN for SEPA)BT-6VAT accounting currency codeNew (0..1)BT-167VAT accounting currency exchange rateNew (0..1, 6 decimal places)Change 8: deprecated business rules (Annex A.4)
The following business rules are removed in the 2026 version:
BR-CO-17VAT = BT-116 x (BT-119 / 100), rounded to 2 decimal placesDecimal places no longer fixed at 2BR-S-10Standard rated: no exemption reason (BT-121/BT-120)Consolidated/revisedBR-Z-10Zero rated: no exemption reasonConsolidated/revisedBR-IG-10IGIC: no exemption reasonConsolidated/revisedBR-IP-10IPSI: no exemption reasonConsolidated/revisedBR-O-2 to BR-O-4, BR-O-11 to BR-O-14"Not subject to VAT": VAT identifiers and breakdown exclusivityConsolidated/revisedCheck your own validation profiles for these deprecated rules when migrating to BIS Billing 4.0/EN 16931-1:2026.
Frequently asked questions
When does EN 16931-1:2026 take effect for Peppol invoices?OpenPeppol is developing BIS Billing 4.0 based on the new standard. The expected production date is 2027. Until that version is available, all Peppol invoices remain subject to current EN 16931-1:2017 with 2 decimal places and existing business rules. eConnect will communicate the transition planning when Peppol publishes the specification.
What does the ISO 4217 'minor unit' mean for my processing?The ISO 4217 minor unit indicates the number of decimal places customary for a currency. EUR, USD and GBP have minor unit 2 (2 decimal places). JPY and KRW have minor unit 0 (0 decimal places). For inbound invoices in multiple currencies, your processing must handle the higher number of decimal places: up to 4 decimal places for amounts, and minor unit + 2 for price descriptions (BT-146/147/148).
Are my EUR outbound invoices affected by the decimal change?No. EUR has ISO 4217 minor unit 2, so the 2-decimal rule continues to apply to EUR invoices. The change only affects invoices in currencies with a different minor unit, and inbound processing for eConnect customers receiving foreign currencies.
Do we need to remove the deprecated business rules from our validator?Yes, when you migrate to EN 16931-1:2026/BIS Billing 4.0. Validators still enforcing BR-CO-17, BR-S-10, BR-Z-10 or the BR-O series may incorrectly reject valid 2026 invoices. Check your validation profile in advance.
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