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MOD 10 Checks validate that a credit card number is in the correct range and format to be a valid credit card number and what card brand is associated with that credit card number.

When a consumer decides to buy on a site the merchant is relying on them to input their information correctly the first time. If you think about this, it may seem simple, but in reality things do go wrong. Consumers could transpose numbers in the sequence, forget one of the digits, forget to input the expiration date or say it’s a Visa card when it’s really an American Express. These things slow down their order processing and clog up the system. And if you don’t do anything to correct this information up front, you open yourself up to the most basic forms of attempted fraud by simply plugging numbers into a site.

The fact that someone gets their credit card number wrong on the buy page does not mean the order is fraudulent. They could have done any of a number of legitimate things to affect the information. If someone repeatedly cannot pass through the MOD 10 check, then it is an issue.

Items to note about the MOD 10 check:

It does not tell you if it the card is active or not, just that it is in the correct format.

This test is used on a website to validate that the credit card submitted is a recognizable credit card number.

Helps to prevent you from processing credit card authorizations on numbers that could not possibly be credit cards.




Alternative Solutions - N/A

Building this In-House - Determine the proper code for your website, then add the MOD 10 code to your customer order page on the submit button.

Estimated Costs - No costs for doing the check, just the initial costs for setting up the code.


The MOD 10 check takes the credit card number the customer submitted and validates that the number is in the correct range and format to be a credit card number and it is the type of credit card the consumer says it is. This is one of the lowest cost and easiest things to implement on your website, and you should implement it now if you are not using it already.

Key considerations when implementing or buying this functionality include:

  • This should be one of the first checks implemented

  • It is very easy to implement

  • Many development sites online offer free snippets of code for completing the MOD 10 Check.


The MOD 10 check is usually implemented right on the website in the web page that contains the buy button and credit card information. The code is a client-side script, so when the customer puts in their purchase information and presses the buy button the MOD 10 checks are done. The order is only sent to the merchant's site when the MOD 10 check passes successfully.

Implementing it this way saves you processing time to go back and forth with the consumer in the order processing. For merchants doing offline authorization it saves you manual intervention time and call-backs. It also saves you money if you are paying each time you call for an authorization.


Since it is a client-side script, you don’t have to do anything with the results. You should not see a consumer order unless they can pass the MOD 10 check.

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