At the ATM, always press 'decline' on the conversion offer — it costs you 6–7%
1 creatorTangerine Travels breaks down exactly how ATM dynamic currency conversion (DCC) works in Mexico: if you accept the ATM's exchange rate offer, you're typically losing 6–7% versus letting your own bank handle the conversion. Most tourists don't know to press the red button that declines this fee — it looks like you're cancelling the transaction but you're actually just refusing the rip-off rate.