From Seller tools > Listings, choose Invoice client beside a product or service. Select an existing customer, quantity, due date and optional message. Tuaneka uses the current invoice-channel price, recalculates the total on the server, creates the invoice and sends it through the normal invoice workflow.
If the recipient email belongs to a registered Tuaneka customer, Tuaneka links the invoice to that user. After verified payment, the purchase is recorded once as an expense in the buyer's active business. The expense stores the original invoice reference and cannot be duplicated by repeated payment callbacks. The buyer can still review and categorize the expense in their own workspace.