Idempotency and external references
Prevent duplicate payment and transfer attempts by designing stable external references and storing request outcomes.
# Idempotency and external references
Prevent duplicate payment and transfer attempts by designing stable external references and storing request outcomes.
## Use one durable reference per business action
Create an external reference before you make a payment or transfer request. Store it alongside the business record and reuse it when you retry the same action after a timeout or uncertain response.
Do not generate a new reference after a network failure. A new reference can turn a retry into a second financial instruction.
## Reconcile uncertain outcomes
When a request times out, keep the operation pending and check its status or wait for the related callback. Mark it complete only when the final state is confirmed.
> **Keep references unique:** External references should be unique within your integration and meaningful enough to trace back to your own order, invoice, or transfer record.