Over Limit

• A credit card transaction might be declined if it would put you over your credit limit. The credit card law that went into effect on February 22, 2010 prohibits issuers from charging a fee for over-limit purchases unless a customer opts in to allow the purchases and pay the fee. Therefore, unless you opt-in, a purchase when you do not have enough available credit will likely be declined.
  
  

Expired Card

• You cannot use a credit card past the expiration date printed on the card. The credit card company will send you a new card about a month before the expiration date. Rather than waiting until the exact date to switch the old credit card out, start using the new card right away. That way you won't run the risk of forgetting and being out shopping with an expired card. Cut up the expired card so you don't accidentally try to use it.
  
  

Incorrect Billing Address

• One of the security features that online credit card processing companies use is the billing address. If you enter your credit card number but the billing address does not match the address your credit card company currently has on file for you, the transaction could be declined. When you move, notify your credit card company of your new address and revise the billing address at any websites at which you have saved your credit card information for easy checkout.
  
  

Card Not Activated

• You usually must activate a new credit card before you can use it for a transaction. This step prevents someone from stealing your mail and using a credit card that was mailed to you. In most cases, there will be a sticker on the card with instructions to call a phone number or visit the issuer's website to activate the card. You will likely have to provide personal information to confirm your identity. Attempting to use a card that is not yet activated will usually result in a declined transaction.