We examine the relationship between credit ratings / changes and audit fees (hours) for Big4 and\ud Non-Big4 firms. Audit fee (hours) may be considered as a default risk metric for credit ratings agencies.\ud However, firms audited by Big4 are larger, better performing and operate with lower leverage compared\ud to firms followed by Non-Big4. Therefore, the association between audit fee (hours) may be different for\ud firms followed by Big4 and Non-Big4 audit firms. We find that there is a negative association between\ud audit fees and credit ratings for firms followed by Big4 audit firms. However, we find an insignificant\ud relation for firms followed by Non-Big4. We conjecture the different association due to the Big4 firms\ud having more robust accounting procedures; Big4 firms must offer competitive audit fees because they\ud are engaged in fierce competition with other Big4 firms. Moreover, Big4 and Non-Big4 firms have\ud different relationships with their clients because Non-Big4 firms are more income dependent on their\ud clients.\ud Using a sample of 1,717 firm–year observations between 2002 and 2013, we establish a relation\ud between audit fees in period t and credit ratings in period t+1, for firms followed by Big4 auditors. We\ud do not find a significant relation for firms followed by Non-Nig4 firms, suggesting that credit ratings\ud agencies perceive audit fee differently for Big4 and Non-Big4 firms. Client firms followed by Big4 auditors\ud that experience a credit rating change in period t+1 pay lower audit fees in period t compared to firms\ud that do not experience a credit rating change. Our additional analysis suggests a different association\ud between firms audit fees and firm performance for firms that experience a credit rating increase and\ud decrease. Firms that experience a credit ratings increase in period t+1 have strong performance and\ud lower audit fees in period t. On the other hand, firms that experience a credit rating decrease have\ud weak financial performance and negative audit fees compared to firms that do not experience a credit\ud ratings change. Our results suggest that audit fees combined with financial performance influence a\ud credit ratings agency' perception of default risk.