In Portugal you are required to declare all foreign accounts opened. The question now is with Revolut and the way law is read. If we consider Revolut as a Bank, then we are required to declare. But if we consider Revolut as a payment service, we are not required. The government is studying the issue. Since Bunq is a digital bank (as N26.com), we are required to declare to tax authority. We already know european countries exchange information. But it will be nice if Bunq in the future will send previously to users the info that will be sending to the tax authority in the country of residence of the user. Currently, as far as I know, only www.ing.lu does that.