Ratepayers Protection Act of 2005 - Requires the Congressional Budget Office (CBO) to study and report to Congress on the effect on certain disadvantaged individuals (e.g., low-income, disabled, and minority groups) of actions taken or considered by regulated electric utilities to reduce their carbon dioxide emissions.

Amends the National Climate Program Act to prohibit: (1) regulated electric utilities from recovering additional costs from ratepayers for reducing carbon dioxide emissions; and (2) state utility commissions from compelling ratepayers to pay any amount incurred by a regulated public utility for reducing carbon dioxide emissions.