> ## Documentation Index
> Fetch the complete documentation index at: https://docs.polygon.technology/llms.txt
> Use this file to discover all available pages before exploring further.

# External accounts

> Customer-owned bank accounts and saved addresses referenced as off-ramp destinations on a transaction.

External accounts are a customer's registered bank accounts and saved blockchain addresses. They are referenced by ID as the destination for off-ramps (fiat out) in a quote or transaction. A quote's source is always an OMS wallet, so external accounts are used as destinations, not sources. OMS never holds funds in an external account, it is a reference used on transactions.

<Note>
  External account registration is not yet available in the OMS API. External accounts are provisioned by Polygon during early-access onboarding. To be notified when registration launches, register your interest.

  <Card title="Register interest" icon="envelope" href="https://info.polygon.technology/get-early-access?utm_source=docs&utm_medium=card&utm_campaign=oms_access">
    Share your use case and we'll reach out when external account registration is available.
  </Card>
</Note>

## Supported types

| ID prefix     | Type                          |
| ------------- | ----------------------------- |
| `pmCard_`     | Debit card                    |
| `cpUsBank_`   | US bank account (ACH or wire) |
| `cpIntlBank_` | International bank account    |
| `cpBcAddr_`   | Blockchain address            |

## Object

```json theme={null}
{
  "id": "cpUsBank_...",
  "object": "externalAccount",
  "customerId": "cst_...",
  "type": "usBank",
  "status": "verified",
  "network": "ach",
  "bankDetails": {
    "bankName": "Chase",
    "accountNumber": "******4242"
  },
  "createdAt": "2025-01-15T10:34:00Z"
}
```

## Using an external account in a transaction

Reference the external account ID under `destination.wallet.externalAccount` in a quote request. The quote `source` is always an OMS wallet, so an external account is used as the off-ramp destination, for example a bank payout (`cryptoToFiat`).

```json theme={null}
{
  "customerId": "cst_...",
  "source": {
    "walletId": "wlt_...",
    "asset": "usdc",
    "network": "polygon",
    "amount": "500.00"
  },
  "destination": {
    "wallet": { "externalAccount": "cpUsBank_..." },
    "asset": "usd",
    "network": "ach"
  }
}
```

## Related

* [Bank transfers guide](/api-reference/guide-bank-transfers): ACH and wire transfer walkthrough
* [Transactions](/payments/transactions): how to use an external account as source or destination