Simpliform Tax Act - Requires the Secretary of the Treasury to, as soon as practicable but in any event not later than 90 days after the date of enactment of this Act, submit to the Committee on Ways and Means of the House of Representatives a draft of any technical and conforming changes in the Internal Revenue Code which are necessary to reflect the changes in the substantive provisions of law made by this Act. Repeals specified provisions of the Internal Revenue Code relating to items of income and deductions. Imposes on the income of every individual a tax of 10 percent. Establishes a surtax on the income of every individual to be computed by the use of a specified table. States that there shall be allowed to an individual as a credit against the tax imposed by this Act for the taxable year in an amount equal to: (1) $250 for the taxpayer, (2) $250 for the spouse of the taxpayer, and (3) $250 for each dependent of the taxpayer who is 18 years of age or older. Establishes rules for determining gains and losses on property owned by a decendent at the time of his death. Sets forth procedures for determining gains and losses on inter vivos gifts. States that there shall be included in gross income monthly insurance benefits paid under title II of the Social Security Act to the taxpayer and any other cash benefits paid to the taxpayer under such Act or any other Act of the United States or of any State providing for the payment of money to individuals in order to enable them to purchase food, clothing, and shelter and otherwise provide for their general welfare. Provides that gross income includes amounts received as prizes and awards, including amounts received as scholarships and fellowship grants.