Skip to content
Change language: English

Warning

UBL-CR-599: A line's VAT category should not carry a per-unit amount

In short

Warning: worth checking.

UBL-CR-599 means the VAT category of an item on an invoice or credit note line has a tax amount per unit (cbc:PerUnitAmount), which EN 16931 does not use. It is a warning. Remove the element without changing the VAT category code (BT-151) or any applicable VAT rate (BT-152).

On this page

What it means

The rule looks at the item on every invoice line (or credit note line) in a UBL file. It warns when the item's VAT details (cac:ClassifiedTaxCategory) contain a cbc:PerUnitAmount, a fixed tax amount for each unit. The warning applies whether or not a VAT category code (BT-151) or VAT rate (BT-152) is also present.

Why it matters

EN 16931 does not use a per-unit tax amount within a line's classified tax category.

How to fix it

Check the export mapping of your invoicing software for a per-unit tax amount in the line's VAT category and omit that element from the export. If you build the XML yourself, delete cbc:PerUnitAmount from cac:ClassifiedTaxCategory under cac:InvoiceLine/cac:Item (cac:CreditNoteLine in a credit note).

Once the file is corrected, check it again for free: Validate an invoice against EN 16931

Or fix the invoice in a form and download the corrected file, for 1 credit: Fix a rejected e-invoice

The rule as published

A UBL invoice should not include the InvoiceLine Item ClassifiedTaxCategory PerUnitAmount

Where this rule applies

Rule set Version
EN 16931 (UBL) 1.3.17
EN 16931 (UBL credit note) 1.3.17
XRechnung 3.0 (UBL) 3.0.2
XRechnung 3.0 (UBL credit note) 3.0.2
Peppol BIS Billing 3.0 (invoice) 2026.5
Peppol BIS Billing 3.0 (credit note) 2026.5
SI-UBL 2.0 / NLCIUS (invoice) 2.0.3.13
SI-UBL 2.0 / NLCIUS (credit note) 2.0.3.13
France CTC (UBL invoice) 1.4.0-04
France CTC (UBL credit note) 1.4.0-04
CIUS-RO UBL Invoice 1.0.9 1.0.9
CIUS-RO UBL Credit Note 1.0.9 1.0.9
Rule text from phive-rules 4.6.4.

Check your file

Drop your e-invoice to see whether UBL-CR-599 still fails, and which other rules do.

Updated 6 November 2026