Surface Transportation Extension Act of 2005, Part III - Extends the authorization of appropriations from the Highway Trust Fund (HTF) for administrative expenses for federal highway, highway safety, motor carrier safety, and transit programs through July 21, 2005. Prohibits, after July 21, 2005, the obligation of funds for any federal-aid highway program project until enactment of a multi-year law reauthorizing the federal-aid highway program.
Amends the Internal Revenue Code to authorize until July 22, 2005, expenditures for obligations under the Transportation Equity Act for the 21st Century (TEA-21) from: (1) the HTF; (2) the Mass Transit Account; and (3) the Aquatic Resources Trust Fund.