Using data from A-share listed companies from 2014 to 2019, we empirically tested the impact of non compulsory tax enforcement on corporate audit fees. The results show that the audit fees of companies with A ratings are significantly lower after the disclosure of tax-paying credit ratings. Furthermore, the decrease of audit fees is more significant for companies with A ratings for three consecutive years and above. The mechanism study suggests that tax-paying credit ratings can reduce corporate audit fees by improving corporate reputation and reducing agency costs. Further, we find that tax-paying credit rating inhibition on audit fees is more significant in non-state-owned companies, situations with intense market competition, poor legal environment and low professional competence. The results provide empirical evidence for the government to innovate tax collection and promote “social integrity construction”.