Countingup accounts do not currently have an IBAN, and cannot directly receive or make international payments.
Payments to other UK bank accounts can be made from within the Countingup app and use the Faster Payments system.
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This is a feature we hope to provide in the future, you can add your support for this on our recently launched community ideas forum at http://community.countingup.com/ideas
In the meantime, we recommend using a service like https://transferwise.com/ to receive international payments into your Countingup account or to make international payments out. It's quick and easy to use and the fees are very low.