It depends on the loan you're trying to get. Bad scores affecting interest rates depends on scoring model, what you're getting a loan for, which of the 3 bureaus are pulled, etc. In general though, credit scores are assigning a risk level to a person. When you make a higher risk bet, you want better return on investment...same as odds in gambling. That's what lenders are basically doing, so it is most likely the answer is YES...interest rate will be higher because that rate determines the return on the lender's investment.