Create Unit.co counterparties and originate ACH and wire payments via the Unit Payments API

Steps

1. Create a counterparty resource by posting to the counterparties endpoint with the routing number, account number, account type (checking or savings), and the counterparty's name; Unit validates routing number format but does not pre-verify account existence
2. Originate an ACH payment by posting to the payments endpoint with type achPayment, referencing the source account ID and the counterparty ID; specify direction (Debit or Credit), amount in cents, and a description that will appear on the bank statement
3. For same-day ACH, set the addenda or sameDay flag (consult current Unit documentation for the exact field name); same-day ACH has three daily submission windows managed by Unit on your behalf
4. For wire payments, post with type wirePayment; include the counterparty ID and a wire message (typically a memo or reference); wires require the counterparty's bank to be wire-capable
5. Poll or receive webhooks for payment status transitions: Pending → Sent → Settled (ACH credit) or Pending → Sent (wire, settles same day if submitted before cutoff)