Below are the possible response code values for offline transactions and their explanations:
| Response Code | Explanation |
| Y1 | Transaction approved offline |
| Z1 | Transaction declined offline |
| Y2 | Transaction approved after referral |
| Z2 | Transaction declined after referral |
| Y3 | Transaction could not go online, but was approved |
| Z3 | Transaction could not go online, but was declined. |
Who Generates These Codes?
In a normal online transaction, the response code is provided by the card-issuing bank and reaches the terminal in field F39 of the ISO 8583 message. For example, approved transactions return the value 00. The codes above that start with Y and Z, however, do not come from the bank; they are generated by the terminal. The terminal uses these codes when it makes a decision without sending the transaction to the bank or without receiving a response from the bank. In EMV, the response code is carried in the 8A tag.
What the Codes Mean
- Y1 / Z1: The transaction was approved or declined offline, as a result of card and terminal checks, without ever being sent online.
- Y2 / Z2: The transaction was approved or declined after a referral process.
- Y3 / Z3: The terminal attempted to send the transaction online, but communication could not be established. In this case, the terminal and the card approved or declined the transaction based on predefined rules.
Why Does It Matter?
Transactions approved with codes starting with Y are not seen by the bank instantly; they reach the bank during the end-of-day batch and clearing process. For this reason, frequent occurrence of codes like Y3 may indicate a problem with the terminal's communication infrastructure. Codes starting with Z show that the transaction was declined without ever reaching the bank. In analyzing customer complaints, these codes are examined to distinguish whether the decline decision was made by the bank or by the terminal.
