What is Business Term (BT) and Business Group (BG) in e-invoice?
Short answer
Business Term (BT) is one specific e-invoice business data defined by the EN 16931 standard, for example BT-1 (invoice number) or BT-110 (VAT amount). A Business Group (BG) is a logical group of several related BTs, for example BG-4 (Supplier Data) or BG-23 (VAT Schedule). Neither BT nor BG are XML elements directly — they are logical concepts that are written into XML according to the chosen syntax (UBL or CII).
For example BT-1, BT-110
Business Term is specific business information with a unique number.
For example BG-4, BG-23
Business Group combines related BTs into a thematic unit.
A logical, not a technical term
In XML, BT/BG are written according to UBL or CII syntax.
In error reports
Both EN 16931 and Peppol BIS Billing rules directly refer to specific BT/BG.
Conclusion
Business Term is one specific piece of data and Business Group is its logical group according to EN 16931 — both serve to uniquely identify the e-invoice content across validation and implementations.
Not legal advice. Machine-translated answer, not yet manually reviewed. For the exact wording, see the Slovak original.