What Is a CSC Code on a Credit or Debit Card?

A Card Security Code (CSC) is an important security feature found on credit and debit cards, designed to protect financial transactions. It helps verify that the individual using the card details is the legitimate cardholder, particularly for purchases made without the physical card present, such as online or over the phone. This code adds a layer of security to help prevent unauthorized use and fraud.

What a CSC Code Is

A Card Security Code (CSC) is a unique, three or four-digit number printed on a credit or debit card, separate from the main card number. Its primary purpose is to protect “card-not-present” transactions, which include online purchases, phone orders, or mail orders, where a physical card cannot be swiped or inserted. The CSC ensures that the person making the transaction has actual possession of the card. Unlike the embossed card number, the CSC is typically flat-printed, making it difficult to capture using older mechanical imprinters.

The term “CSC” serves as a general umbrella term, but various card networks use their own specific names for this security feature. Visa refers to it as Card Verification Value (CVV), while Mastercard calls it Card Verification Code (CVC). American Express and Discover commonly use the term Card Identification Number (CID). Other names include Card Verification Number (CVN) or Card Authentication Value (CAV).

Locating Your CSC Code

Finding your Card Security Code (CSC) on a credit or debit card is straightforward, though its exact location and length can vary depending on the card network. For Visa, Mastercard, and Discover cards, the CSC is typically a three-digit number. This code is usually found on the back of the card, often in or near the signature strip. It may appear as the last three digits of a longer number printed there.

American Express cards, however, feature a four-digit CSC. This code is located on the front of the card, usually printed above or to the right of the main embossed card number. If you cannot locate the code, contacting your card issuer can provide assistance.

The Role of CSC Codes in Security

Card Security Codes enhance the security of card-not-present transactions by acting as an additional verification step. When you make an online or phone purchase, merchants request this code to confirm that the person providing the card details physically possesses the card. This process helps mitigate fraud by making it harder for unauthorized individuals to use stolen card numbers and expiration dates without the corresponding security code.

An important aspect of CSC security is that merchants are generally prohibited from storing these codes after a transaction is authorized. This rule is a component of the Payment Card Industry Data Security Standard (PCI DSS). By not retaining the CSC, even if a merchant’s database is compromised, the stolen card data would lack this important security element, making it more difficult for fraudsters to conduct unauthorized online purchases. This non-storage requirement ensures that the CSC acts as a dynamic verification tool, proving physical card possession at the time of each transaction.