Fairness for Working Americans Act of 2004 - Amends the Internal Revenue Code to: (1) eliminate the reduction in the percentage of earned income for calculating the refundable portion of the child tax credit (15 to ten percent) for taxable years beginning before 2005; (2) include in earned income for purposes of calculating the refundable portion of the credit otherwise tax excludable combat zone compensation of members of the armed services; and (3) set forth rules for the tax treatment of certain foreign corporations engaging in tax avoidance activities as U.S. domestic corporations.