If you do not qualify for a credit card you may need a cosigner to help you obtain a credit card. Usually, a cosigner is a close relative. For example, for teenagers who have not yet had an opportunity to establish their own credit histories, having their parents to be cosigners on the credit card application will, in most cases, increase the chances of obtaining a credit card A good cosigner is generally someone with an excellent credit/payment history and/or more-than-sufficient available funds and income to be able to pay for your credit card bill if you are unable to for any reason.