Abusive Tax Shelter Shutdown and Taxpayer Accountability Act of 2003

[AI summary unavailable — showing source text] Abusive Tax Shelter Shutdown and Taxpayer Accountability Act of 2003 - Amends the Internal Revenue Code (Code) concerning tax shelters to, among other things: (1) define economic substance; (2) impose a penalty for the failure to include in a return information concerning a reportable transaction, a reportable transaction understatement (including imposing the penalty for certain understatements which were based on unreasonable legal or factual assumptions), a noneconomic substance transaction understatement, and interests in foreign financial accounts; (3) modify rules concerning the failure to furnish information regarding reportable transactions and the penalty for such failure, the failure to maintain lists of investors in potentially abusive tax shelters and the penalty for such failure, the authority to seek an injunction to enjoin promoters of abusive tax shelters; and (4) deny a deduction of interest on underpayments attributable to nondisclosed reportable transactions and noneconomic substance transactions. Amends other Code provisions to, among other things: (1) place a limit on the transfer or importation by a corporation of built-in losses; (2) provide for the partnersh…