Internal Revenue Service

United States government agency

Also known as: IRS

Written and fact-checked byThe Editors of Encyclopaedia Britannica

Updated: Nov. 12, 2026

Also Known As:: IRS

Areas Of Involvement:: taxation

News

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IRS announces 2027 401(k) contribution limits, raises savings cap: What it means for your money • Nov. 12, 2026, 12:23 PM (ET)(CNBC)

Internal Revenue Service, Agency of the U.S. Department of the Treasury charged with administering and enforcing federal tax laws, except those relating to alcohol, tobacco, firearms, and explosives. It issues rulings and regulations to supplement the provisions of the Internal Revenue Code; determines, assesses, and collects internal revenue taxes; and determines exempt organization status.