Advances and final invoices

Reserve an accepted advance on a final-invoice draft with POST /outgoing-invoices/{invoiceId}/advance-applications. This prevents two final invoices from consuming the same amount. Release a draft reservation with the corresponding DELETE route.

Mandatory order

accepted advance → reservation → reversal of used advance amount → final invoice with BG-3 reference

During issuance, Klik Račun freezes settlement, creates and completes the reversal for each used advance, and only then issues the final invoice.

Raw UBL matching

When raw UBL contains one billing reference and a nonzero PrepaidAmount, Klik Račun finds the accepted local advance by number and date. For multiple advances, use the JSON UBL envelope with explicit advanceApplications.

The submitted final invoice may identify the business advance. Klik Račun creates the required reversal and enriches the effective UBL with references to the actual reversal documents, so the integrator does not have to predict their numbers.