As a merchant, understanding how a PIN (Personal Identification Number) works with credit and debit card transactions is essential for running a secure and efficient payment process. Whether you operate a physical store or an e-commerce business, being informed about the role of PINs can help you prevent fraud, ensure smooth transactions, and provide a safer shopping experience for your customers.
This guide explains how a PIN functions in credit and debit card payments and its importance for merchants.
What is a PIN?
A PIN is a four- to six-digit numerical code assigned to a credit or debit card by the card issuer or chosen by the cardholder. The purpose of a PIN is to authenticate the identity of the cardholder during a transaction. In a payment scenario, the PIN helps confirm that the person using the card is authorized to do so.
For merchants, this layer of security is critical. It protects you from unauthorized transactions that could lead to chargebacks or losses. A PIN system is typically used when customers pay with their debit cards or, in some cases, credit cards—especially for transactions involving cash advances.
How Does a PIN Work?
When a customer uses a credit or debit card at your store, the transaction follows a specific process if a PIN is required. Understanding how this works will help you ensure your payment systems are functioning correctly.
Card Presentation: The customer inserts or taps their card at the point-of-sale (POS) terminal, which may require PIN entry depending on the card type and transaction.
PIN Entry: Your terminal prompts the customer to enter their PIN on the keypad. This ensures that only the person who knows the PIN can authorize the payment.
PIN Encryption: Once the customer enters the PIN, it is encrypted immediately to protect the information. Encryption ensures the PIN cannot be intercepted or stolen during transmission.
Verification: The encrypted PIN is sent to the card issuer’s system, where it is matched against the cardholder’s stored PIN. If the PIN is correct, the transaction proceeds. If the PIN is incorrect, the system will decline the payment.
Transaction Approval: Upon successful verification, the card issuer approves the transaction, and the payment is processed. If the wrong PIN is entered too many times, the card may be temporarily blocked.
PINs for Debit Cards vs. Credit Cards
Debit Cards: For merchants, debit card transactions almost always require the customer to enter a PIN. This is because funds are drawn directly from the customer’s bank account. PINs ensure an additional layer of security, protecting both the cardholder’s funds and your business from fraudulent activity. At the point-of-sale, your system will prompt for the PIN whenever a debit card is used.
Credit Cards: Depending on the country and type of transaction, PIN entry may not be required for standard credit card purchases. However, in some regions, like Europe, credit cards use the chip-and-PIN system, where every transaction requires PIN entry instead of a signature. For merchants who accept international payments, understanding this system is key. Additionally, cash advances from credit cards, such as those at an ATM, always require a PIN.
PINs in Contactless Payments
Contactless payments, often referred to as “tap-and-go” transactions, have become increasingly popular due to their speed and convenience.
Contactless payments allow customers to make purchases by simply tapping their card or mobile device (such as a smartphone or wearable) on a contactless-enabled point-of-sale (POS) terminal. These payments use Near Field Communication (NFC) technology to transmit payment information securely. The key benefit for both merchants and customers is the speed—there’s no need to insert a card, swipe, or manually input information.
In most contactless payments, a PIN is not required for lower-value transactions, typically up to $100–$250 depending on the region. However, for higher-value purchases or when a customer reaches a cumulative transaction limit, the system may prompt for a PIN or card insertion for security reasons. Mobile wallets using biometric authentication generally bypass the need for a PIN. Merchants should ensure their POS systems are updated and staff are trained to handle these scenarios to maintain a smooth and secure payment experience.
Why is a PIN Important?
For merchants, the PIN plays a vital role in reducing fraud and protecting your business from losses due to unauthorized transactions. Here’s why it matters:
Fraud Prevention: A PIN significantly reduces the chances of unauthorized use. Even if a card is lost or stolen, the person using it will need the correct PIN to complete a transaction. This extra layer of security lowers the risk of fraudulent activity in your business, which can otherwise lead to chargebacks or disputes.
Reduced Chargebacks: Chargebacks happen when a cardholder disputes a transaction, claiming it was unauthorized. If a transaction was authorized with a PIN, the chances of a successful chargeback are reduced, as the PIN proves that the rightful cardholder was present.
Security for Your Customers: Offering secure payment methods builds trust with your customers. When they know their transactions are protected by a PIN, they are more likely to shop confidently, which can lead to higher satisfaction and repeat business.
Compliance with Card Network Requirements: Many card networks and issuers require merchants to use PIN authentication for certain types of transactions, particularly for debit cards. Failing to comply with these rules can result in penalties, fines, or additional fees for your business.
What Happens if the Wrong PIN is Entered
When a customer enters an incorrect PIN at your POS terminal, the transaction will be declined. Typically, the customer will have a few attempts (usually three to four) to enter the correct PIN. If the wrong PIN is entered multiple times, the card may be temporarily locked to prevent unauthorized access.
From a merchant’s perspective, it’s important to know that repeated incorrect PIN attempts don’t affect your business directly but can create inconvenience for the customer. You may need to assist them with alternatives, such as a signature-based payment or another form of payment.
How to Ensure Secure PIN Transactions
As a merchant, you have a responsibility to maintain secure payment environments. By following these best practices, you can ensure PIN-based transactions are safe for both your business and your customers:
Invest in Secure POS Systems: Ensure that your POS terminals are up-to-date and comply with the latest security standards, including encryption of customer PINs during transactions. Terminals should be PCI DSS (Payment Card Industry Data Security Standard) compliant.
Regularly Update Payment Software: Software updates often include important security enhancements. Make sure your payment systems are updated regularly to protect against fraud and potential breaches.
Encourage Customers to Protect Their PIN: Remind customers to cover the keypad when entering their PIN and to avoid sharing their PIN with others. While this is their responsibility, merchants can foster an environment where security is a priority.
Train Your Staff on Payment Security: Educating your employees on the importance of PIN security can help prevent fraud. Make sure your staff knows how to handle sensitive transactions, monitor suspicious activity, and assist customers if issues arise during PIN entry.
Avoid Storing Customer PINs: Your payment systems should never store customer PINs. By ensuring that PINs are encrypted and never retained by your systems, you reduce the risk of data breaches and maintain compliance with industry regulations.