The creditor is required to respond to the dispute within 30 days and has a maximum of 90 days to investigate and resolve the error. (debt.org)
Federal law states that the credit card issuer must respond to a dispute in writing within 30 days. (creditdonkey.com)
This is the minimum amount of time it takes for credit bureaus, creditors and collection agencies to respond to your dispute letters. (mycreditgroup.com)