> For the complete documentation index, see [llms.txt](https://doc.bunq.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://doc.bunq.com/psd2/card-based-payment-instrument-issuer-cbpii.md).

# Card-Based Payment Instrument Issuer (CBPII)

{% hint style="success" %}
Heya! Before checking this page, make sure that you [registered yourself as a TPP](/psd2/are-you-a-third-party-provider-tpp-start-here/register-as-a-tpp.md) in our API first.
{% endhint %}

As a CBPII, you are allowed to authenticate in a user’s account to validate the availability of funds for the payment in question.

1. Collect an alias for the bunq user's account (their name and IBAN, email address, or phone number).
2. Check the availability of funds via `POST /user/{userID}/confirmation-of-funds` passing the following information:
   * your `userId`;
   * the amount of money needed for the payment;
   * the name of the bunq user and the IBAN of the account (email address or phone number pointing at the user are also possible).

Here is the full specs of the endpoint:

{% openapi src="/files/xJ3v0GinyfONRbxz8Srh" path="/user/{userID}/confirmation-of-funds" method="post" %}
[swagger.json](https://346554585-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FGE9Y1hc6C24r4Hen6KFH%2Fuploads%2Fgit-blob-218d6e618d396b5e315e30f903e92e143f7a4cc1%2Fswagger.json?alt=media\&token=108cfcc1-06ec-4015-875d-12120194eb40)
{% endopenapi %}


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