In this years' Annual Report to Congress, National Taxpayer Advocate, Nina E. Olson states that "without a doubt, the largest source of compliance burdens for taxpayers and the IRS alike is the overwhelming complexity of the tax code, and without a doubt, the only meaningful way to reduce these compliance burdens is to simplify the tax code enormously".
2004 Annual Report to Congress - Volume I
2004 Annual Report to Congress - Volume II [contains an interactive Table of Contents]
2004 Annual Report to Congress Executive Summary