Imprisonment for Tax Targeting of Americans Act of 2013 - Amends the Internal Revenue Code to provide for a mandatory fine and prison term of five years (currently, not more than five years) for: (1) unauthorized disclosure of tax return and return information and for unlawful solicitation to obtain such information, and (2) unauthorized inspection of tax returns or return information. Imposes a mandatory fine and a prison term of not more than five years for willful oppression under color of law by U.S. revenue officers and employees (currently, a fine or a prison term, or both, may be imposed).