> ## 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.

# Debit cards

> Use a debit card as an on-ramp funding source or an off-ramp payout destination in OMS.

A debit card connects to OMS in two directions. As a **funding source**, a card payment converts to USDC and tops up a customer's wallet (an on-ramp). As a **payout destination**, OMS pushes a wallet balance out to a cardholder's debit card (an off-ramp). Both run through the standard quote-and-transaction flow; only the asset, network, and destination reference change.

<Note>
  Debit card external accounts (`pmCard_`) and on-ramping via a debit card are part of early-access onboarding rather than through a public endpoint. To be notified when debit cards launch, please 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 debit card support is available.
  </Card>
</Note>

## Two roles

| Role               | Transaction    | What happens                                              | Reference                                 |
| ------------------ | -------------- | --------------------------------------------------------- | ----------------------------------------- |
| Funding source     | `fiatToCrypto` | A card payment converts to USDC and credits a wallet      | Source `asset: usd`, `network: card`      |
| Payout destination | `cryptoToFiat` | A wallet balance is pushed to the cardholder's debit card | Destination `externalAccount: pmCard_...` |

## Card as a funding source

A card-funded on-ramp uses the `card` rail on the transaction source. The customer pays with their debit card and OMS delivers USDC to the destination wallet.

```json theme={null}
{
  "customerId": "cst_...",
  "source": {
    "asset": "usd",
    "network": "card",
    "amount": "100.00"
  },
  "destination": {
    "wallet": { "id": "wlt_..." },
    "asset": "usdc",
    "network": "polygon"
  }
}
```

The quote and transaction structure follows the standard [fiat-to-crypto](/payments/guides/fiat-to-crypto) flow.

## Card as a payout destination

A debit card is registered as an [external account](/payments/external-accounts) with the `pmCard_` prefix, then referenced by ID as the destination of a `cryptoToFiat` transaction. OMS pushes the payout to the card. As with all external accounts, the quote source is always an OMS wallet, so a card is used as a destination, never a source.

```json theme={null}
{
  "customerId": "cst_...",
  "source": {
    "walletId": "wlt_...",
    "asset": "usdc",
    "network": "polygon",
    "amount": "100.00"
  },
  "destination": {
    "wallet": { "externalAccount": "pmCard_..." },
    "asset": "usd",
    "network": "card"
  }
}
```

## Related

* [Currencies and rails](/payments/core-concepts/currencies-and-rails): the full list of supported assets and rails
* [External accounts](/payments/external-accounts): registering a `pmCard_` debit card as a payout destination
* [Transactions](/payments/transactions): the quote-and-execute flow for card and bank transfers