This POST endpoint is used to store user attributes, allowing you to associate additional data with a user token.
To use this endpoint, you need to provide the user_token, endpoint_token, and currency as parameters in the URL Path. You also need to provide the attribute values as JSON parameters in the Request body.
If existing attributes are already stored for the user, this call will create a new attr_set_token.
When the attribute type is SocialSecurity or EIN, the transaction is allowed to proceed while the number and name are validated against IRS records in the background. The result of this validation is delivered via a webhook under the kyc.tax event.
If the SSN or EIN does not match the name on file with the IRS, the user will be prompted to re-enter it the next time they attempt to initiate a transaction. At that point, the user should update either their name or their SSN/EIN.