How to pay by QR code in Vietnam using a foreign banking app?

When ready to pay, clearly say 'banking QR' to the vendor. Do not show your phone screen or mimic tapping it to a terminal — staff will assume you want to pay by card. Once they display the QR code, scan it with your app, enter the amount in Vietnamese dong, and confirm.

If the app throws an error when trying to pay, try logging into the same account from a different phone. The card or payment method can only be set up through the mobile app, not via a browser.

Vendors are not familiar with foreign banking app interfaces, so showing them your screen will not help. Simply saying 'banking QR' is enough for them to understand which payment method you want to use.