Records a payment made to the supplier against a purchase order (approved, partially received or received; drafts and cancelled POs are rejected with 400). The PO's payable is its received value — cost + tax of its non-voided receives, landed costs excluded — so a payment made before the goods arrive (a deposit) is accepted and shows as overpaid (negative outstanding_amount; payment_status_text reads "Advance" while nothing is received yet) until receives catch up. A payment that would take the PO's total paid past the larger of its ordered total and its received value is rejected with 400. Requires the approve-purchase-orders permission at the PO's location.

Amounts are always in the company currency, also on a foreign-currency PO (convert with the PO's currency.rate: foreign = amount / rate). Receipts (transfer slips) are attached from the Ewity web app; file upload is not part of the documented App API, so payments recorded by an App carry receipt: null.

The payment method's own configuration decides what else is required, as on the POS: a method with refRequired needs a non-blank reference (labelled by the method's refText, e.g. "Cheque number"), and a bank-transfer method with transferReceiptRequired needs an attached receipt. A payment missing either is rejected with 422 (reference / receipt_file_id). As Apps cannot attach receipts, a method that requires one cannot be used from an App.