The most important fields of an e-invoice (BT numbers)
Validation messages and specialist documents often name fields only by their BT number. This reference explains the most common ones so you know where an error is.
Updated on 28 October 2026
How to read the numbers
BT stands for “business term”. Every field of the European norm has a number. If a validator reports an error at BT-10, for example, look here to see which field is meant.
Header data
The details of the invoice itself:
- BT-1: invoice number
- BT-2: date of issue
- BT-3: invoice type (for example invoice or credit note)
- BT-5: invoice currency
- BT-9: due date
- BT-10: buyer reference, for public authorities the Leitweg-ID
- BT-13: order number
- BT-24: specification identifier
Seller and buyer
Who delivers and who receives:
- BT-27: name of the seller
- BT-31: VAT identification number of the seller
- BT-32: tax number of the seller
- BT-44: name of the buyer
- BT-84: payment account, for example the IBAN
Line items
Single lines of the invoice:
- BT-129: quantity
- BT-146: net price per unit
- BT-131: net amount of the line
- BT-153: item name
- BT-118: tax category of the line
- BT-119: tax rate
Totals
The amounts at the end of the invoice:
- BT-106: sum of the lines (net)
- BT-109: total without tax
- BT-110: total tax amount
- BT-112: total with tax
- BT-115: amount due
Assigning errors
If totals do not add up, the cause is usually in BT-106 to BT-112: rounding, missing lines or a wrong tax category. The validation result names the fields concerned.
Frequently asked questions
- Do I have to fill all these fields?
- No, only the mandatory fields of the chosen specification. A validator reports missing mandatory fields.
- Where can I find the complete list?
- In the norm EN 16931 and in the XRechnung specification. This reference shows only the most common fields.
- Why are the fields named so cryptically?
- The numbers are independent of language and apply in all EU countries.
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More guides
- Tax categories in the e-invoice
- Understanding and fixing validation messages
- XRechnung: structure and mandatory fields
These guides do not replace tax or legal advice. For questions about your own case please ask your tax adviser.