My dad needs a kidney transplant and he asked me. Am I an automatic match since im his child or is it possible I can't do it?

Not necessarily. There are two issues when matching for organ transplantation: blood group matching and hla matching (immune compatibility). As is the case with blood transfusions, blood types generally need to be matched for successful transplantation to take place. Although there are some centers that will perform transplants despite mismatched blood types, these are more prone to reject.
You must be tested . You must be tested for match to determine if can donate and compatible.