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Error

FX-SCH-A-000870: An invoicee fax contact needs exactly one number

In short

Error: fails the selected checks.

FX-SCH-A-000870 means a fax entry in the invoicee's contact has no number or more than one. Give ram:FaxUniversalCommunication exactly one ram:CompleteNumber, or remove the fax entry.

On this page

What it means

The contact of the invoicee, the party the invoice is sent to when that is not the buyer, can have a fax number. If the fax element is present, it must hold exactly one number (ram:CompleteNumber). An empty element and an element with two numbers both fail.

Why it matters

The number is read from one fixed place. If it is missing or doubled, the recipient's system cannot tell which number is meant, so the file fails the check and may be rejected.

How to fix it

Check the fax field of the contact on the invoice address in your invoicing software. Fill in one number or clear the field so that no empty entry is written. Most invoices do not need a fax number at all. If you build the XML yourself, the number goes in ram:CompleteNumber inside ram:FaxUniversalCommunication, exactly once.

Once the file is corrected, check it again for free: Validate a ZUGFeRD invoice

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

The rule as published

Element 'ram:CompleteNumber' must occur exactly 1 times.

Where this rule applies

Rule set Version
Factur-X 1.09 EXTENDED 1.0.9-2
ZUGFeRD 2.5 EXTENDED 2.5.2
Rule text from phive-rules 4.6.4.

Check your file

Drop your e-invoice to see whether FX-SCH-A-000870 still fails, and which other rules do.

Updated 5 November 2026