Law Portals

• FindLaw (Tax Law)
• Hieros Gamos (Taxation Law, US)

Laws, Regulations, Opinions

• Internal Revenue Code (Cornell LII) 
• Internal Revenue Code (GPO)
  • Regulations
    • To access: choose TITLE 26
  • Statutory Code
    • To access: choose year, then TITLE 26
• Internal Revenue Code
  • Historical back to 1994. To access: choose year, then TITLE 26
• Internal Revenue Manual
• U.S. Tax Court

Federal Government

• Internal Revenue Service
• Internal Revenue Manual 
• United States Congress. Joint Committee on Taxation
• United States Congress. House. Committee on Ways & Means

Associations

• American Bar Association, Section on Taxation
• Federation of Tax Administrators
• Multistate Tax Commission

Forms

• 1040.com
• IRS Forms

General Sites

• Tax History Project