Fighting Tax Fraud Act of 2012 - Amends the Internal Revenue Code to impose an increased penalty on a tax return preparer who engages in fraudulent conduct by: (1) willfully modifying any tax return or claim for refund which creates an understatement of tax liability after such return or claim has been signed by the taxpayer, and (2) willfully attempting to intercept the proceeds of such modified refund or claim. Establishes the penalty amount at the greater of $5,000 or the amount of the understated tax liability.