No matter what types of accounts you open, your credit score will always be yours and yours alone. Even getting married and opening a joint bank account won't merge your credit score with your spouse. However, any credit information from the joint account will affect both owners of the account.

Credit Score Effects

When your name is on a joint account, both you and the other person on the joint account are responsible for the account. So, if you overdraw account and don't pay it back, that shows up on both your credit report and the other joint account holder's credit report. However, any other accounts that the joint account holder has that your name isn't on won't affect your score.