Many ATMs (and merchants) will pick up that your card was issued in the UK. Once these machines realise that your card is a UK-issued card it doesn’t recognise that you hold the local currency and will offer you a conversion. This is called Dynamic Currency Conversion (DCC).
In order to avoid this extra charge please always select to be billed in the local currency, for example, if you are in the Eurozone always select to be billed in EUR.
For further information about DCC, refer to our article.