If your account has a variable rate, the interest rate is tied to an index that can change.  The credit union can change your interest rate periodically when the index changes.  Your credit card account agreement will explain when changes to your variable rate can occur. 

If your account does not have a variable rate, there are important limits on when your interest rate can change.  If you opened your account on or after February 22, 2010, the credit union generally cannot change your interest rate during the first year after the account was opened.  After the first year, the credit union can change your interest rate, but it has to give you 45 days notice in writing before the change takes effect.  In addition, the new interest rate will only apply to transactions that occurred more than 14 days after the notice was provided.

There are exceptions to the general rule. For instance, if you agreed to an introductory interest rate that ends after at least six months, or you are more than 60 days late in making a required payment, the credit union can increase the interest rate that applies to your existing balances and new transactions.

If you opened your account before February 22, 2010, the credit union does not have to wait 12 months after your account is opened to raise your interest rate for new transactions.  However, it still has to give you 45-days advance notice in writing before the interest rate change goes into effect. 

Be sure to review your credit card account agreement, which is the contract governing your credit card account.  It provides information on changes that may occur to your account.