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Credit Card
Yes. American Express cards have a 4-digit CVV on the front and a 3-digit CVV on the back, like other cards. Here's how payment forms should handle both formats and why logging the security code is never allowed.
Chargeback
A chargeback is the process of requesting that an amount paid by credit card be refunded, either because the goods or services paid for were not received, or because a transaction is identified as one the cardholder did not carry out.
Payment Systems
Every payment transaction completes in seconds, yet dozens of controls run behind the scenes. This post covers the precautions for authorization and clearing, the critical role of reversals, and the financial loss scenarios most often seen in the field.
Credit Card
The '12 - Invalid Transaction' error is usually returned when the issuer declines the transaction. It typically occurs when the same card is tried repeatedly at the same merchant for the same amount in quick succession.
Payment Systems
In payment or cash withdrawal transactions, the TR QR Code is generated by the POS or ATM. The card issuing bank must build its systems to read and act on this code. Errors usually stem from mishandling the long and short QR code flows, which are explained here.
Merchant & POS
In payment systems, every exchange between POS devices and bank or payment institution systems runs on a specific messaging standard, generally based on ISO 8583. However, each country, bank, or switch network defines its own version of this standard.
Credit Card
You start a transaction at an ATM and your card is returned, even though you think nothing is wrong. Here are the response codes usually used in these cases.
Payment Systems
Online PIN is verified by the card-issuing institution through the message itself, while Offline PIN is verified on the chip. This article explains the difference and when PIN bypass is allowed.
Merchant & POS
Partial Authorization lets an issuer approve part of a transaction instead of declining it when the balance or limit is insufficient. This post covers how it works in ISO 8583, whether it is mandatory, and why it matters for the business.
Merchant & POS
A reader asked whether installment mail order transactions are still possible, and whether a card limit equal only to the installment amount is enough. This article shares the answer.
Fraud
Fraud monitoring refers to tracking card transactions through scenarios to detect potential fraud and taking rapid action immediately before or after a transaction occurs - such as identifying a suspicious transaction, calling the customer, or temporarily blocking the card to prevent authorization.
Contactless
A TR Karekod transaction is a payment carried out using a QR code generated according to the procedures and principles in the regulation on the generation and use of the TR Karekod in payment services.