Credit cards generally have to be activated before you can use them. However, not activating the card doesn't mean the account isn't valid. Once a credit card application is approved, the account is opened and the card is issued. If you don't want the card, you'll need to properly cancel the account to avoid fees and potential credit consequences in the future.
When you open a new credit account, whether you activate the new card or not, it's still classified as an open account in the eyes of the credit card issuer and credit reporting agencies. The credit card issuer can legally report the card to the credit bureaus each month. However, if you aren't using the card, there may be nothing to report.
Whether you activate the card or not, a hard inquiry will show up on your credit report. When you applied for the credit card, you gave the issuer permission to review your credit, which results in a hard inquiry. Although inquiries have a minimal impact on your score, too many could raise red flags. Expect the inquiry to remain on your credit report for 24 months, but it will only affect your score for the first 12 months. If there's an annual or monthly maintenance fee, you can be charged even if you aren't using the card.
A pre-approved credit card offer isn't the same as an card you didn't activate. You're free to ignore pre-approval letters without them affecting your credit.
Replacing an Expired Card
If you receive a new card to replace an expired card linked to an established account, you'll need to close the account if you don't want to activate the card. If you don't plan on using the card, the credit card issuer can close the account due to inactivity.
If you've had a credit account for several years, losing the established account can hurt your credit score. Your credit card utilization rate can also drop when you lose the available credit.
Canceling the Card
If you don't like the terms or the interest rate associated with the credit card, contact the credit card issuer immediately to state that you don't want the card. You may need to send a written request, depending on the credit card issuer's protocol. Bankrate suggests asking the issuer to send you written documentation confirming the account was closed. Keep records of any correspondence with the credit card company, including a log of phone calls and letters. If a maintenance or annual fee was charged to the account, you may be required to pay that before the account can be closed. Since you never activated the card or used it, the issuer may be willing to waive the fees. After confirming the card is canceled, destroy it.