| Variables | Definitions | |
| LNFEE | Log of audit fees | |
| TA (Tax avoidance) | ETR | Effective tax rate calculated by the formula (1) |
| Ratediff | Difference between nominal tax rate and the effective tax rate | |
| MaETR | Average of ETR from year t − 4 to year t | |
| MaRatediff | Average of MaRatediff from year t − 4 to year t | |
| Controls | SIZE | Log of total assets |
| DFL | Financial leverage, | |
| RISK | Inventory and receivables, scaled by total assets | |
| ROA | Return on total assets | |
| TAT | Total asset turnover | |
| LOSS | A dummy variable that equals 1 if a firm reports net losses and 0 otherwise | |
| OP | A dummy variable that equals 1 if a firm receives an uqualified audit opinion, and 0 otherwise | |
| BIG4 | A dummy variable for audit firm size and equals 1 if it is one of the Big 4, and 0 otherwise | |