Using www.irs.gov, find the publication related to Form 1040 and research how to calculate taxable income for individuals. Discuss whether this source is a primary or a secondary source of federal income tax law. Also research the Internal Revenue Code and find the section that defines gross income. Then find another section of the Internal Revenue Code that specifically excludes an item of income from the definition of gross income. Discuss whether the Internal Revenue Code is a primary or secondary source of tax law.