I have a Mastercard and use it to buy books. I buy a lot of books, over $100,000 per year easily and it is not unusual for me to buy, say, $5000 worth of books on a single day from multiple vendors who may be from the USA, Canada, UK, France and other places, mostly in Europe.

The problem is that frequently this triggers Mastercard's automated fraud prevention system and they lock my card and cancel all my transactions which is extremely annoying because it damages my relationship with the book dealers and prevents me from using the card to, for example, buy gas.

I talked to a bank representative and they said the only thing they can do is to temporarily remove fraud protection from the card for up to a week. The representative said that they have no way to whitelist particular vendors or particular types of purchases.

How can I solve this problem?

  • 2
    Does this happen even after you continue to patronize the same vendor? Normally, fraud detection is about patterns. Otherwise, have you tried using a different card?
    – pboss3010
    Commented Feb 14, 2020 at 14:51
  • 2
    Are you sure that the problem is Mastercard? Because with Visa, at least, it's the issuing banks that are responsible for fraud protection. I agree with @pboss3010 about getting a card from a different bank.
    – RonJohn
    Commented Feb 14, 2020 at 15:01
  • 2
    Do you have a regular old consumer Mastercard, or a business oriented one? These sorts of volumes wouldn't faze a bank if it's on a business account.
    – ceejayoz
    Commented Feb 14, 2020 at 15:13
  • @RonJohn technically, the network and the issuing bank are both involved in fraud detection. For instance, Mastercard stops some transactions on their own, but they also hand us a fraud score and we can choose a threshold within our system to stop additional transactions (and, of course, we calculate our own fraud score and use that too).
    – dwizum
    Commented Feb 14, 2020 at 16:19
  • Not exactly a solution, but I'd suggest getting several other cards. Then you'd at least have one to pay for gas, and possibly could rotate the ones you use to avoid triggering fraud protection logic.
    – jamesqf
    Commented Feb 14, 2020 at 18:08

1 Answer 1


The card issuer's software is looking for patterns, an anomaly to your regular spending. At year end, when I am making a series of online cash donations to charity, more than once my card got frozen. I called the card issuer and told them the details to prove I was me, and they unfroze the card. They also suggested a phone call before I made my annual donations.

Similarly, I call them when a family member will travel outside our usual area. If they suddenly multiple charges in a foreign country, they might freeze the card.

In your case, the card issuer should be happy to talk to you about how to note on the account that this type of buying will occur on a regular basis. They should want your business and make it as easy for you as possible, including using appropriate fraud protection that doesn't impact you this way.

  • 2
    Further, you may want to talk to your issuing bank about other products they have. For instance, most banks have a commercial card product that has fraud detection configured to be more in line with how Five Bagger is describing their card use. They may be able to switch you to a different product and avoid the problem.
    – dwizum
    Commented Feb 14, 2020 at 16:21

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