I will be buying a car soon and I wanted to know when I get my check checked and if my dad will be my co-signer will they also check my moms credit history? She has soon bad points on her credit history. Since my parents are still married I wanted to know if they check their credit indivdually.

Unless your Dad has co-signed for your mom, her credit mistakes will not affect your Dad's credit. They will check your Dad's credit only.