Generate a new IBAN that will produce a given scenario on the sandbox, for example a rejected loan. Each IBAN can be used as the account of a single counterparty or borrower (a buyer or seller of yours). So, if you want to test the API for several of your counterparties, you will have to generate several of them. The BIC associated to these IBANs is FK2FACTO. Also, if you want to test another scenario on a given business, create a new IBAN and use it in the <code>to_account</code> field of the next invoice and loan that you create for this counterparty. For more information on the scenarios of the sandbox, please refer to the <a href="https://developers.getdefacto.com/reference/testing-your-integration">Testing Multiple Scenarios & Errors</a> section. Warning: these IBANs will not work in production.