How does USAA determine the exchange rate used in international ATM transactions?


I am asking because I withdrew money from an ATM in Mexico on March 31 and April 1, 2020.

I used the same ATM and withdrew the same amount (8,000 pesos) each time.

But the amount in US$ taken from my USAA account was $5.36 more on April 1 than on March 31.

I find this odd because the Peso to US$ exchange rate on April 1 was higher than on March 31.

On April 1 the rate was above 24 pesos to 1 US$ and on March 31 is ranged between 23.5 to 24 pesos. 

So the amount in US$ taken from my account on April 1 should have been less than on March 31, not more.


@BHott, hi there! Exchange rates can flucuate daily.  The rate used is determined by the bank you are withdrawing from at that time.  When they process this to us, they send over all the information to debit the account.  Hope this helps.