Extend Tax Cuts bill

Relief for Working Families Tax Act of 2003 - Title I: Child Tax Credit - (Sec. 101) Amends the Internal Revenue Code (Code) to: (1) accelerate the refundability of the child tax credit to the 15 percent rate to make it effective in 2003 (currently, 2005); and (2) include combat pay (otherwise excludable from gross income) as earned income for purposes of determining such refundability.(Sec. 102) Increases the threshold amount, for joint filers, applicable to the child tax credit to $115,000 for 2008 and 2009 and setting it at $150,000 beginning in 2010. Provides that such amount, for a married individual filing separately, shall be one-half the amount of a joint return. (Maintains the current threshold amount of $75,000 for single filers.)(Sec. 103) Applies the sunset provisions of the Economic Growth and Tax Reconciliation Act of 2001 to this title.Title II: Uniform Definition of Child, Etc. - (Sec. 201) Rewrites the provision defining the term "dependent" in the Code and modifies head of household, dependent care credit, child tax credit, earned income credit, personal exemption, and other provisions to be consistent with such definition.Title III: Customs User Fees - (Sec. 301) Amends the Consolidated Omnibus Budget Reconciliation Act of 1985 to extend customs user fee authority until March 31, 2010.