Omer et al. (2006) find that,
especially prior to SOX, one-year-ahead marginal tax rate (MTR) and ETR reductions
are associated with higher tax fees paid to audit firms. This result supports
our contention (and DGM’s noted limitation) that controlling for tax planning is
necessary to determine the extent to which firms manipulate tax expense to achieve
earnings targets. Given the findings of Mills et al. 1998 and Omer et al. 2006, we
expect that firms with higher levels of tax fees paid to auditors have greater thirdto-
fourth-quarter ETR reductions relative to companies that spend less on auditorprovided
tax services: