XRechnung Mandatory Fields: Every Required BT with UBL Path and Rule

XRechnung mandatory fields are the business terms (BT) without which the KoSIT validator rejects an XRechnung 3.0.2 file. Without any condition, that covers 41 fields and groups: header data such as BT-1 and BT-10, the name, city and electronic address of both parties, a seller contact, a payment means code, four totals, a VAT breakdown and seven fields per line.

This page is written for integration teams and foreign suppliers who map their ERP data to XRechnung. Every row below gives the UBL path, a sample value and the rule that enforces the field. The rule texts come from the KoSIT validator configuration 2026-08-31 (XRechnung Schematron 2.6.0, CEN Schematron 1.3.16). XRechnung (the German CIUS of EN 16931) applies when you invoice German public authorities, and many German companies request it for B2B invoices too.

Who needs this checklist?

• Suppliers outside Germany who invoice a German authority and get a rejection from the federal or state portal.
• ERP and billing teams building an XRechnung export, who need exact paths rather than a list of field names.
• Accounts payable teams in Germany who must decide whether an incoming file can be processed.

For the format basics, read what XRechnung is. For namespaces, the root element and the CII alternative, see the guide to the XRechnung XML structure. All paths below use UBL 2.1 and are relative to the root element Invoice. CII uses the same BT numbers with different element names.

The checklist: unconditional XRechnung mandatory fields

Two rule sets apply together. Rules named BR- without a country code and BR-CO- come from EN 16931 and apply across Europe. Rules named BR-DE-, plus the Peppol rules PEPPOL-EN16931-R… that KoSIT includes, apply to XRechnung only. Every rule listed has the level "error" unless marked "warning".

Document header

For public-sector buyers, BT-10 holds the Leitweg-ID (the German buyer reference for authorities). A missing BT-10 triggers BR-DE-15. BT-23 is optional in EN 16931, but the XRechnung rules require it. BT-24 also selects the validation scenario: an outdated identifier matches no scenario in the current configuration, and the file is rejected before any field rule runs.

Seller (BG-4)

Path prefix: cac:AccountingSupplierParty/cac:Party.

The seller contact group is a common gap in ERP exports built for other countries, because EN 16931 itself does not require it.

Buyer (BG-7)

Path prefix: cac:AccountingCustomerParty/cac:Party.

Payment, totals and VAT

A file without any payment instructions fails with BR-DE-1. EN 16931 lets you omit BT-119 when the invoice is not subject to VAT; XRechnung requires it in every VAT breakdown through BR-DE-14.

Invoice line (BG-25, at least one under BR-16)

Path prefix: cac:InvoiceLine.

A complete file with these values is available as the XRechnung example. A line-by-line walkthrough of a similar invoice is in the e-invoice example for Germany.

Special cases: conditional mandatory fields

Many fields become required only when another field has a certain value. These conditions cause a large share of portal rejections, because master data is usually set up for the standard case only.

The payment groups exclude each other. A credit transfer (30 or 58) must not carry a card or direct-debit group (BR-DE-23-b). Foreign suppliers often hit BR-DE-16 when their ERP stores the VAT ID only in a free-text field: it must sit in cac:PartyTaxScheme.

What the validator does not enforce: gaps against § 14 UStG

The XRechnung mandatory fields and the invoice requirements of Section 14(4) of the German VAT Act (§ 14 UStG (opens in a new tab)) overlap only in part. A file can pass validation and still lack a VAT-law item.

Two gaps matter in practice. First, the street: the rules require only city, post code and country code for both parties. In our own test with configuration 2026-08-31, a sample invoice without either street line was accepted. Second, the delivery date: BR-DE-TMP-32 is information-level and never blocks a file.

The reverse also holds. XRechnung requires fields that German VAT law does not mention: buyer reference, business process, electronic addresses, seller contact and payment means code. Without them the file is not a valid XRechnung, even if every § 14 item is present. How the German tax authorities classify such defects is covered in format errors versus content errors. The full list of VAT-law items, with special cases, is in German invoice requirements.

How to document the check

1. Technical result: the validation against the KoSIT rules, with the date and the configuration version (here 2026-08-31). For a report to keep on file, run the KoSIT validator itself.
2. Content check: tick off the items the validator does not enforce, such as street, delivery date and exemption note.
3. Storage: keep both records with the XML file, not just with a PDF rendering.

If you issue invoices, test one file per customer type after each master-data change: a German authority with a Leitweg-ID, a private B2B customer, a customer with a separate delivery address, and an exempt or reverse-charge supply. This surfaces conditional fields before a real invoice is rejected.

How to check XRechnung mandatory fields with docutools.pro

1. Open the XRechnung validator and upload your .xml file (UBL Invoice or CII). Without a file of your own, use "Load sample invoice". The file is sent to our server for the check. The free plan allows 2 uploads per day up to 500 KB; the Pro plan removes these limits.
2. Read the "KoSIT validation" section. It checks the way the KoSIT validator does (configuration 2026-08-31) and lists each finding with its rule ID and the level "Error" or "Warning". A missing mandatory field shows up as, for example, BR-DE-15 or PEPPOL-EN16931-R020.
3. Match each rule ID to a field and UBL path with the tables above. For background on single codes, use the reference of XRechnung error codes, for example BR-DE-2 for the seller contact group.
4. Then check what the validator does not enforce. Open the German invoice requirements checker, choose "XRechnung/ZUGFeRD XML" and click "Auto-check XML". On XML import, the tool always marks the delivery date, exemption note and discounts as missing, so tick them by hand after reading the file. The checker runs in your browser and the file does not leave your computer.
5. If a field such as BT-10, BT-34 or the street is missing, fix the master data in your billing system and export again. Smart Repair in the viewer cannot add a Leitweg-ID, an address or a contact.

More field-level guides are collected under more guides on XRechnung.

Sources

• KoSIT: Validator configuration XRechnung, release 2026-08-31 (opens in a new tab), with XRechnung Schematron 2.6.0 and CEN Schematron 1.3.16 (rule texts and levels)
• XStandards Einkauf: XRechnung specification and versions (opens in a new tab)
• German Federal Ministry of Justice: § 14 UStG, issuing invoices (opens in a new tab)

Last reviewed: October 2026

This article is general information, not tax or legal advice.