S Corporation Modernization Act of 2007

S Corporation Modernization Act of 2007 - Amends the Internal Revenue Code to revise the tax treatment of S corporations, including by: (1) reducing from 10 to 7 years the period during which S corporation built-in gains are subject to tax; (2) allowing nonresident aliens to qualify as beneficiaries of an electing small business trust (ESBT); (3) repealing mandatory termination of S corporation elections for excessive passive investment income; (4) allowing S corporations to increase passive investment income from 25 to 60% without incurring additional tax; (5) allowing individual retirement accounts to be S corporation shareholders; and (6) allowing ESBTs to claim expanded charitable tax deductions.

Directs the Comptroller General to study and report to Congress on entity neutrality under the Internal Revenue Code with respect to S corporations, limited liability companies, and other pass-through entities.