Why is a modification missing credit card details?

For most modifications, you won’t receive the guest’s credit card details. This is because, for security reasons, we only send the full card details in the first pull. If the price, date or room are modified, you’ll only receive the relevant details in the modification message.

However, if the credit card itself has been updated in the system, you will receive the full credit card details.

For some examples of modification messages, check out the following links:

B_XML: https://connect.booking.com/user_guide/site/en-US/b_xml-reservations/

OTA:  https://connect.booking.com/user_guide/site/en-US/ota-resmodifynotif/