Algorithm tests is what is used to validate most credit cards around the world since it can be easily modified to fit validation requirements and rules which differ from one country to another. The rules that can be applied when validating a card are many but the company in question will choose specific ones to validate based on the security needs and the preferences.

Recognition of the provider

The first rule most companies or merchants will use to validate a card is through the provider recognition. This is determined by the first two or up to six digits of the card. In Australia and other countries where the MasterCard is used, the digits are normally 51-55 whereas those of the American Express card begin with 34-37. Each card type differs in the number of digits it has although the first ones are the codes which will lay the first protection foundation when handling a card.

The Expiration Date

Every single card number has a date of expiration which is the best credit card qualifier. When the date does not match the information the credit provider has or has already expired, then it must be declined or rejected as it is invalid.


The zip code and the address is another rule of validating a credit card since this is one piece of information that will never be left out when a card is being issued. This way, it is hard for unauthorised person to use a card since it is hard to have such information that most take for granted. This is a good way of getting a card verified since this information is not physically written on the card but is something that the owner should know off head if he is the genuine cardholder.

Security code

Technology has made it easy for hackers and fraudsters to acquire card numbers illegally and using them for transactions especially online. The security code is however hard to obtain unless you have the card physically with you. The code is normally made of three digits found on the back side of the card and is normally at the end of the card number. Companies use this validation rule to confirm that indeed the card is in the rightful hands.


Although not commonly used, the signature found on the back side of a card can be a rule of validation. The signatures could be used to compare with what appeared on the identification forms. But this was way before the card underwent the electronic changes before machines were available. This was done manually with those not matching the identification card or driver’s license being declined by merchants or companies.

The above rules are applied in most countries of the world including Australia and better ones are hoped to be developed in the near future to counter the tricks that fraudsters and hackers are using in obtaining money or getting services and products that they do not pay for genuinely and instead use other people information.