⚠️ Experimental endpoint — not yet a stable contract. This action ships as experimental / beta. While experimental, its schema and behaviour may change without a version bump — including breaking changes within v1.0 itself. Anyone consuming it does so for evaluation only, or by coordinating adoption with their account manager so changes can be sequenced with them. It graduates to a stable, version-locked contract (where the normal breaking-change rules apply) only when this experimental notice is removed.

Issue a full credit note cancelling the given partner invoice. The credit note copies the original's seller, buyer, currency and payment terms, copies every line item with its amounts, and references the cancelled invoice via referenceId. It is issued with paymentStatus unpaid and carries no amountPaid — credit notes do not track payments. Only one credit note may exist per invoice. Partial credit notes are not supported.

Eligibility depends on the B2B invoice processor recorded on the invoice at issuance. An invoice generated through the built-in B2B invoice integration is eligible as soon as it is issued. An invoice generated through a processor that certifies documents with a fiscal authority is eligible only after the original document has been certified — until the document exists at the fiscal authority there is nothing to cancel. Use fiscalization.status on the single-invoice read to observe this: pending and failed mean not yet creditable, certified means the precondition is met. Certification is a necessary, not a sufficient, condition — the rare certified document with no recorded fiscalization.referenceNumber described under fiscalization.status stays ineligible and requires operator intervention.

A 425 means the original document has not been certified with the fiscal authority yet, so there is nothing to cancel. Retry once fiscalization.status on the single-invoice read reaches certified.