This study investigates whether the relation between the tax risk and audit fees as well as audit hours. Specifically, we utilize tax risk measures that are designed to capture greater taxrelated uncertainty, including each of four measures of firms risk related to the volatility of taxable income (hereafter TI_VAR), the covariance between taxable income and book income (hereafter BT_COV), the volatility of cash or GAAP effective tax rates (hereafter CASH ETR_ VAR, GAAP ETR_VAR), and the volatility in book-tax differences (hereafter BTD_VAR) over five years (the current year and the previous four years). Each of these measures captures tax decisions that potentially impose significant costs on firms and thus, should influence the market’s assessment of future after-tax cash flows. Recent research in the tax literature suggests that tax risk is an important construct, and numerous studies have introduced potential academic tax risk measures (e.g., Hutchens and Rego, 2015; Dhaliwal et al., 2017; Guenther et al., 2017 etc.). The effects of tax risk have been discussed in almost every decision context in the extant tax literature, but the relationship between tax risk and auditing has amazingly merited little attention. We explore the relationship between tax risk and auditor pricing as well as auditor effort measured as audit hours. In this study, we investigate whether greater tax risk is associated with increased audit risk, thus tax risk that affect audit pricing and auditors’ additional audit effort. Therefore, we test our prediction that auditors assess higher audit fees and audit hours on client with higher levels of tax risk. Thus, we test four hypotheses about the relation between tax risk and audit fees as well as audit hours. In additional analysis, we next examine whether the effect of tax risk according to accruals quality proposed by Francis et al.(2005) have differential impact on the audit risk by auditors. For analysis, we consider four additional proxies for tax risk in our empirical tests. First, we follow Dhaliwal et al.(2017) use the volatility of taxable income (TI_VAR), which is the standard deviation of taxable income deflated by lagged total assets calculated for years t-4 through t. Second, we follow Dhaliwal et al.(2017) use the covariance between book income and taxable income (BT_COV), which is the correlation between pretax book income and taxable income deflated by lagged total assets calculated for years t-4 through t. Then, we measure BT_COV is (-1) times, thus higher value of BT_COV indicate increased tax risk. Third, we use the volatility of annual both cash effective tax rates or GAAP effective tax rates over the five prior years (CASH ETR_VAR, GAAP ETR_VAR), which is the standard deviation of cash taxes paid or tax expense divided by pretax income calculated over years t-4 through t as a proxy for tax risk from Hutchens and Rego(2015) and Guenther et al.(2017). Lastly, we use the volatility in booktax differences (BTD_VAR), which is the standard deviation of book-tax difference scaled lagged total assets calculated over years t-4 through t as our fourth proxy of tax risk proposed by this study. This study sample covers KOSPI and KOSDAQ listed firms in non-financial industries with fiscal year-end in December from 2003 to 2016 period. Our main sample consists of 6,582(6,584) firm-year observations in audit fees (audit hours) data. We document several findings. First, after controlling for several factors that affect audit fees and audit hours, we find evidence consistent with our hypothesis that there is a positive and significant association between TI_VAR and audit fees as well as audit hours. In addition, we find that there is a positive and significant association between BT_COV and audit fees as well as audit hours. This result suggests that auditors perceive the volatility of taxable income and will be decreasing in the covariance between book income and taxable income as a risk factor that they incorporate into audit fees and hours. Also, these results provide evidence that both TI_VAR and BT_COV provide incremental information about audit risk beyond the volatility of book income as a additional control variable in our test. Second, we also include the GAAP ETR_VAR in the model, we find evidence consistent with our hypothesis that there is a positive and significant association between GAAP ETR_VAR and audit fees as well as audit hours. Nevertheless, it is still positive and significant coefficient TI_VAR as well as BT_COV measures. In contrast, we include CASH ETR_VAR in the model, we find no significant association between CASH ETR_VAR and audit fees as well as audit hours. Third, we also include BTD_VAR, BT_COV, and ETR_VAR in th model, we find evidence consistent with our hypothesis that there is a positive and significant association between BTD_VAR and audit fees as well as audit hours. Nevertheless, it is still positive and significant coefficient GAAP ETR_VAR measures. In contrast, we find no significant association between BT_COV and audit fees as well as audit hours. This is, higher BT_COV do not appear to be associated with increased audit risk even when controlling for BTD_VAR and ETR_VAR, as a additional test variable in our test. Therefore, compared to BT_COV proxy, BTD_VAR is recognized as indicators of audit risk by auditors. Lastly, when we also divided the full samples into high accruals quality and low accruals quality subsamples, according to the median level of accruals quality, we find that a positive and significant relation between tax risk measures and audit fees as well as audit hours is more pronounced among low accruals quality samples than high accruals quality samples. Therefore, this results suggest that low accruals quality drives the association between tax risk and audit risk by auditors. Overall, this study increases our understanding of which tax risk metrics capture tax-related uncertainties that lead to assessments by auditors of higher audit risk. In particular, our results suggest that the volatility of taxable income, the volatility of GAAP effective tax rates, and the volatility in book-tax differences over five years are superior proxies for a firm’s exposure to tax risk that leads to increased uncertainty about a firm’s future cash flows. Consequently, we shows that auditors, on average, perceive higher values for each of these tax risk metrics to be related to an increase in audit risk. More importantly, we find that the positive association between tax risk and audit fees as well as audit hours is more pronounced for firms with low-quality accruals. Thus, our study makes several contributions to the tax research as well as auditing literature. To the best of our knowledge this is the first study to examine the relation between tax risk and audit fees as well as audit hours. Together, our research increases our understanding of which tax risk metrics capture tax-related uncertainties that lead to assessments by auditors of higher audit risk, which serves as an important empirical evidence to academics as well as investors, tax authorities, regulators, and policymakers may provide useful information.