Government Accountability and Streamlining Act of 2003 - Requires the Comptroller General, to the extent practicable, to prepare for public bills and joint resolutions (measures) reported by congressional subcommittees or committees, and submit to such subcommittees or committees, determinations of whether: (1) new Federal entities, programs, or functions are authorized by the measure; and (2) an existing entity or program carries out functions that are similar to those authorized by the measure and such existing entity or program may more effectively and efficiently perform the functions and carry out the purposes of the measure than the proposed entity or program.
Requires such statements to accompany reports on legislation.