There is a growing awareness that federal tax law caters to a small number of wealthy and well-advised taxpayers without regard for the rest of the taxpaying public, and partnership tax is a prime example. This Article explains how complexity and indeterminacy have transformed partnership tax, harming millions of forgotten taxpayers who struggle to comply with their annual filing obligations. A root cause of this phenomenon is the professional culture among elite practitioners, policymakers, and scholars at the heart of the partnership tax system. The most troublesome provisions of partnership tax are also its most fundamental—namely the allocation rules that regulate how partners share a partnership’s taxable items. Complexity is a univers...