There are a number of websites with useful information about tax law. You may find some of the following helpful:
Internal Revenue Service and Publications
♦ Internal Revenue Service home
♦ Internal Revenue Bulletins, 1996-present
♦ IRB 2003-27 - present
♦ IRS Electronic Reading Room of IRS documents
♦ IRS Forms and Publications
♦ Internal Revenue Manual
Other Government Documents and Publications
Executive
♦ Code of Federal Regulations (1996 - current)
♦ Federal Register, 1936-present
♦ Federal Register Tutorial
♦ United States Government Manual
♦ Weekly Compilation of Presidential Documents
Legislative
♦ Congressional Bills, 103rd. Congress (1994-95) - present
♦ Public and Private Laws, 104th Congress (1995-96) - present
♦ Congressional Record Bound, Vol. 1 (1873) to Vol. 162 (2016)
♦ Congressional Record Daily (1994 to present)
♦ Congressional Record Index (1983 to present)
♦ U.S. Code (1994 to present)
♦ GAO Reports and Comptroller General Decisions, 1989 - 2008
Congress and the "Money Committees"
♦ House of Representatives
♦ Senate
The Taxing Committees
♦ House Ways and Means Comm.
♦ Senate Finance Comm.
The Appropriations Committees
♦ House Appropriations Comm.
♦ Senate Appropriations Comm.
The Budget Committees
♦ House Committee on the Budget
♦ Senate Budget Committee
Joint Economic Committee
♦ Joint Economic Committee - Senate
Joint Committee on Taxation
♦ Joint Committee on Taxation
Judicial
♦ U.S. Tax Court
Selected Government Sites
♦ A Century of Lawmaking 1774-1875 (Includes Serial Set, Bills, Statutes at Large, etc.)
♦ Criminal Tax Manual (USDOJ, 2012 edition)
♦ Govinfo.gov
♦ Regulations.gov
♦ USA.gov
♦ U.S. Dept. of Justice Tax Division
♦ U.S. Dept. of the Treasury
New York State
♦ NY State Dept. of Taxation and Finance
New York City
♦ NYC Dept. of Finance
Bar Associations
♦ ABA Section of Taxation
♦ NY State Bar Association Tax Section
Note: The Tax Section Reports are available at this site.
International Taxation
♦ Income Tax Treaties (IRS)
Research and Tax Pathfinders
Tax Research
♦ Georgetown Law Library Guide (Scroll down for several Tax Research guides)
♦ Duke Law Library Guide
Evaluating Web Sources
♦ Evaluating Web Pages