How to indicate the deduction of advances in the billing e-invoice?
Short answer
In Peppol BIS, already paid payments are shown by default in the PrepaidAmount element as the amount paid in advance. It should not be mechanically replaced by negative lines in the InvoiceLine if it is a deduction from a received payment. PrepaidAmount is part of LegalMonetaryTotal and reduces the amount to be paid.
Prepaid amount
Amount paid before billing.
Not a regular delivery
A deposit is not a new negative good or service.
Surcharge
The resulting payment amount is calculated after deducting the deposit.
Correct mapping
Internal negative lines must be converted to the correct Peppol structure.
Conclusion
The deduction of the already paid advance in the billing e-invoice belongs to PrepaidAmount (BT-113), not to impromptu negative items, if it is a payment made before billing.
Financial Administration of the Slovak Republic, FAQ 9/DPH/2025/IM for e-invoice, update July 2026
Not legal advice. Machine-translated answer, not yet manually reviewed. For the exact wording, see the Slovak original.