One of the "quick wins" I recommend to retailers in improving their conversion rates by reducing cart abandonment is to explain what the credit card security code is, why it's asked for and where to find it. We take it for granted that many people don't know the "security code" or CVV2 (card verification value) asked for in the checkout process can be found on the backside of their credit cards. CVV2 is used to reduce fraud for card-not-present transactions. (Not all online retailers require the CVV2 so this tip only applies to retailers who do).
Often the checkout form looks like this, with no explanation of what the security code is, where to find it and why it is asked for:
I usually suggest using a link that says "What is this?" with more information in a mouseover. I recently spotted AT&T doing one better -- showing exactly where to find the number using an image:
Remember that different cards have different CVV2 locations, so mention that.
This tactic could easily be saving AT&T millions in sales each year. Why don't you try it?
Another reason customers may hesitate to provide the CVV2 code is the erroneous belief that they are actually risking their personal information more by providing the super-secret code. They feel like you're not just asking for an email address but a password too!
Of course, the fact you're asking for the CVV2 code is proof you value their security - you're preventing anyone who's stolen their card number from making a fraudulent purchase. But customers don't see it that way. Reassure them that the CVV2 code is NOT stored in a database and is only used in card-not-present transactions for preventing fraud.
These 2 point-of-action assurances (showing the CVV2 visually and reassuring CVV2 is not stored in a database) should have a positive influence on your conversion rate if you are required to ask this information from customers.