Public-domain · open source
OpenJurist

Tax Law

Permalink

Compiled from primary legal sourcesNot legal adviceHow we source this

Tax law governs the obligations of individuals and businesses to pay taxes and the rules by which governments assess and collect them. It is a broad and technical field that touches nearly everyone, from everyday filers to large organizations.

Common matters include understanding tax obligations, preparing for and responding to audits, disputing the amount a taxing authority claims is owed, addressing unpaid taxes and related penalties, and planning transactions or activities in a tax-conscious way. It spans personal income taxes, business taxes, and other forms of taxation, and it involves both compliance and the resolution of disputes.

Key concepts a non-lawyer should understand include the difference between lawful tax planning and unlawful evasion; the idea that taxing authorities have defined processes for audits, assessments, appeals, and collection; and the principle that there are usually formal ways to challenge or negotiate a disputed tax bill rather than simply accepting it. Tax matters are also typically governed by strict timelines.

People and businesses typically consult a tax lawyer when facing an audit or investigation, when they disagree with a tax assessment, when dealing with significant tax debt, or when planning a major transaction with important tax consequences. Legal guidance helps clarify obligations and the options for resolving a dispute.

Share of classified federal decisions

1861187519001925195019752000200750%0
share of classified federal decisions

Of the federal decisions we've classified by topic, the share each year that fall under this practice area — so a persistently high line means this is a large, enduring share of federal litigation. This is not a share of all litigation: only part of the corpus is topic-classified (unevenly across eras), and an opinion can belong to several areas, so areas need not sum to 100%. State cases are largely unclassified, so this is federal only. The dip in the last several years is a data-coverage gap — our corpus holds fewer opinions from the most recent years — not a real decline.

Circuit splits in tax

Legal questions the federal courts of appeals are divided on — each links to the cases creating the split.

From the OpenJurist Bookshop

View all Tax Law books →

Sub-practice areas

More specific practice areas within Tax Law — narrower topics that fall under it, each with its own page.

Related practice areas

Tax Debt and IRS Disputes LawBonds and Government Finance LawAdministrative LawCivil Rights LawConstitutional LawElection Campaign and Political LawEnvironmental LawFalse Claims Act Law

Primary law

The governing U.S. Code, statutes and founding documents for Tax Law.

Key definitions

Defined terms that recur in tax law — each links to its dictionary entry.

TaxIncome TaxAuditIncomeDeductionAssessmentAbatementDepreciationExemptionLevyLienDeficiency

Landmark cases (9)

Landmark cases are the Supreme Court decisions that defined or reshaped Tax Law — establishing the controlling principles courts still apply. Current law leads; where a decision overruled an earlier landmark, the superseded case is shown beneath it.

Superseded decisions

Key cases of the U.S. Courts of Appeals

The most-cited decisions applying U.S. Code Title 26 (Internal Revenue Code) — beyond the landmark cases above.

Frequently asked questions

Tax Law by state

Courts, law libraries and state-specific resources. State law governs much of this area, so deadlines and rules vary by state.

Further reading

  • A Practical Guide to Valuation for Rating - Paperback
    A Practical Guide to Valuation for Rating - Paperback
    Luke Wilcox
  • Corporation Tax Act 2010 (c. 4) - Paperback
    Corporation Tax Act 2010 (c. 4) - Paperback
    United Kingdom Legislation
  • International Law of Taxation - Paperback
    International Law of Taxation - Paperback
    Peter Hongler
  • Mr. Taxpayer Versus Mr. Tax Spender: Taxpayers' Associations, Pocketbook Politics, and the Law During the Great Depression - Paperback
    Mr. Taxpayer Versus Mr. Tax Spender: Taxpayers' Associations, Pocketbook Politics, and the Law During the Great Depression - Paperback
    Linda Upham-Bornstein
  • Antitrust and the Formation of the Postwar World - Paperback
    Antitrust and the Formation of the Postwar World - Paperback
    Wyatt Wells
  • The Book on Advanced Tax Strategies: Cracking the Code for Savvy Real Estate Investors - Paperback
    The Book on Advanced Tax Strategies: Cracking the Code for Savvy Real Estate Investors - Paperback
    Amanda Han
  • Leach's Tax Dictionary - Paperback
    Leach's Tax Dictionary - Paperback
    Robert Leach
  • The New Income Tax Scandal: How the Income Tax cheats workers out of MILLION$ each year and the corrupt reasons why this happens - Hardcover
    The New Income Tax Scandal: How the Income Tax cheats workers out of MILLION$ each year and the corrupt reasons why this happens - Hardcover
    J. Christopher Garrison
  • Value Added Tax - Paperback
    Value Added Tax - Paperback
    Alan Schenk
  • Advanced Issues in International and European Tax Law - Paperback
    Advanced Issues in International and European Tax Law - Paperback
    Christiana Hji Panayi
  • A Practical Guide to Challenging Seizures under the Customs and Excise Management Act 1979 - Paperback
    A Practical Guide to Challenging Seizures under the Customs and Excise Management Act 1979 - Paperback
    Paul Tapsell
  • Media Law: A Practical Guide (Revised Edition) - Paperback
    Media Law: A Practical Guide (Revised Edition) - Paperback
    Ashley Messenger
  • Every Airbnb Host's Tax Guide - Paperback
    Every Airbnb Host's Tax Guide - Paperback
    Stephen Fishman
  • Beware the Commerciality Doctrine and Other Nonprofit Law Poetry - Paperback
    Beware the Commerciality Doctrine and Other Nonprofit Law Poetry - Paperback
    Bruce R. Hopkins
  • The Evil California Franchise Tax Board - Paperback
    The Evil California Franchise Tax Board - Paperback
    Adrian Vance
  • Home Business Tax Deductions: Keep What You Earn - Paperback
    Home Business Tax Deductions: Keep What You Earn - Paperback
    Stephen Fishman
  • Antitrust Consent Decrees in Theory and Practice:: Why Less Is More - Paperback
    Antitrust Consent Decrees in Theory and Practice:: Why Less Is More - Paperback
    Richard A. Epstein
  • U.S. Taxes for Worldly Americans: The Traveling Expat's Guide to Living, Working, and Staying Tax Compliant Abroad (Updated for 2026) - Hardcover
    U.S. Taxes for Worldly Americans: The Traveling Expat's Guide to Living, Working, and Staying Tax Compliant Abroad (Updated for 2026) - Hardcover
    Olivier Wagner
  • How To Be a Successful Philanthropist - Paperback
    How To Be a Successful Philanthropist - Paperback
    Bruce R. Hopkins
  • A Sourcebook of Income Tax Law in Tanzan - Paperback
    A Sourcebook of Income Tax Law in Tanzan - Paperback
    F. D. A. Makinyika Luoga
  • The Application of the OECD Model Tax Convention to Partnerships, A Critical Analysis of the Report Prepared by the OECD Committee on Fiscal Affairs - Paperback
    The Application of the OECD Model Tax Convention to Partnerships, A Critical Analysis of the Report Prepared by the OECD Committee on Fiscal Affairs - Paperback
    Michael Lang
  • Insurance Premium Tax: A User's Guide - Paperback
    Insurance Premium Tax: A User's Guide - Paperback
    Mark Chesham
  • Implied Trusts and Beneficial Ownership in Modern UK Tax Law - Paperback
    Implied Trusts and Beneficial Ownership in Modern UK Tax Law - Paperback
    Chris Thorpe
  • A Comparative Analysis of Tax Administration in Asia and the Pacific - Paperback
    A Comparative Analysis of Tax Administration in Asia and the Pacific - Paperback
    Asian Development Bank

This overview is general legal information, not legal advice, and does not create an attorney–client relationship. Laws vary by state and change over time — consult a licensed attorney about your situation.