Child Tax Fairness Act of 2003 - Amends the Internal Revenue Code to: (1) provide a uniform definition of the term "child"; (2) repeal the head of household filing status and establish an exemption of $3,700 for single taxpayers with either a qualifying child, relative, or parent in the household; and (3) exempt means-tested government benefits when determining whether or not over half the cost of a dependent's care is provided by a taxpayer.