Exempt Organization Simplification and Taxpayer Protection Act of 2013 - Amends the Internal Revenue Code to: (1) require an organization that intends to operate as a tax-exempt social welfare organization to notify the Secretary of the Treasury of such intent with information as to its identity and purpose, (2) allow such an organization to seek a declaratory judgment concerning its status and classification as a tax-exempt organization, and (3) authorize the Secretary to disclose information for investigations of violations of internal revenue laws relating to unauthorized disclosure or inspection of tax information and unlawful acts of revenue officers or agents.

Directs the Comptroller General (GAO) to study and report on the process used for determining how Internal Revenue Service (IRS) enforcement cases are selected and processed.

Prohibits any IRS officer or employee from using a personal email account to conduct official business.