Discover Payment Decline Code
Discover Decline Code 66: Card Acceptor Call Acquirer Security Department
Category Fraud or SecurityRetry Guidance Conditional Decline (Editorial Classification)By Payment Defender Editorial TeamUpdated July 17, 2026Last reviewed July 17, 2026
What Discover Decline Code 66 Means
Discover decline code 66 (Card Acceptor Call Acquirer Security Department) indicates that the card acceptor is instructed to call the acquirer's security department.
Where the Response May Come From
Code 66 asks the merchant to call the acquirer's security department, signaling a security-related acceptance condition. It points to the acquirer relationship, so the acquirer's security team is the reference for resolution.
Common Reasons for This Response
Common causes include acquirer security conditions requiring merchant contact.
Should the Merchant Retry the Payment?
A retry is discouraged until the acquirer security review is complete; whether a later attempt succeeds depends on that outcome, so confirm before reprocessing.
Recommended Merchant Action
Contact your acquirer's security department as instructed before reprocessing, and offer the customer an alternate method in the meantime.
What to Tell the Customer
Let the customer know the payment needs additional review and offer an alternate way to pay in the meantime.
How to Reduce Similar Payment Failures
Logging code 66 events and escalating to your acquirer promptly helps resolve security-related acceptance conditions without repeated failed attempts.
Important Limitations
Decline-code meanings vary by processor, gateway, and payment environment, and issuers do not always disclose the specific reason behind a response. The retry classification on this page is Payment Defender editorial guidance, not an official network rule. Merchants should confirm handling with their processor or gateway.
Related Decline Codes
Sources and Review Information
Last reviewed July 17, 2026
Raw network-response codes are supplemental to the complete processor or gateway response. Meanings and recommended actions can vary by issuer, processor, gateway, card network, payment method, region, and merchant configuration.