Stewart Karlinsky & Laura R. Ingraham (both of San Jose State University) have published Tax Professionals’ Perception of Small-Business Tax Law Complexity, 107 Tax Notes 79 (Apr. 4, 2005), also available on the Tax Analysts web site as Doc 2005-6090, 2005 TNT 64-35:

The authors report in this article on their study in questionnaire format that tested the perception of 89 small-business tax practitioners regarding the complexity of 37 tax provisions. They found overwhelming consistency on the five most complex and five least complex small-business tax provisions with partnerships, estate and gift valuations, tax-deferred exchanges, frequency of law changes, and retirement plans topping the hit parade. Progressive tax rates, estimated taxes, Social Security/self-employment taxes, corporate capital gain provisions, and cash versus accrual method were uniformly and consistently perceived as the least complex. These results have tax policy implications. According to the authors, for example, a House bill to move S corporations to a partnership regime may not be optimal from the simplification perspective. The authors question whether familiarity with an issue results in lower perception of complexity. There is some discussion in the tax policy literature about tiering (different tax rules for small versus large companies). That policy seems to have made certain tax areas (cash versus accrual, depreciation, installment sales, and possibly corporate alternative minimum tax and uniform capitalization (UNICAP) less complex for small-business practitioners.