What does booking verification identifies as a high-risk booking?

When performing a booking verification, the following cases are the most common reasons for a booking to be identified as "high-risk":

• The card does not hold sufficient funds.
• The bank declined the card validity.
• The card will expire before the check-in.
• The card is a prepaid card.
• The country of card issuance is different from the country in which the booking was made.

Receiving a high-risk booking does not mean the client is a fraudster. 

It rather means that IF the client is a fraudster or a no-show, it is highly unlikely you will be able to bill the card. So, to be on the safe side, you should contact your client and ask for a valid card.