Government Accountability and Streamlining Act of 2005 - Requires the Comptroller General, to the extent practicable, to prepare for, and to accompany, each public bill and joint resolution reported by a congressional subcommittee or committee a determination of whether: (1) the measure authorizes new Federal entities, programs, or functions; (2) an existing entity or program carries out functions similar to those authorized by the measure; and (3) the existing entity or program may more effectively and efficiently perform the functions and carry out the measure's purposes than the proposed entity or program.