26 CFR Chapter I – INTERNAL REVENUE SERVICE, DEPARTMENT OF THE TREASURY
- Chapter I, Subchapter A – INCOME TAX
- Chapter I, Subchapter B – ESTATE AND GIFT TAXES
- Chapter I, Subchapter C – EMPLOYMENT TAXES AND COLLECTION OF INCOME TAX AT SOURCE
- Chapter I, Subchapter D – MISCELLANEOUS EXCISE TAXES
- Chapter I, Subchapter F – PROCEDURE AND ADMINISTRATION
- Chapter I, Subchapter G – REGULATIONS UNDER TAX CONVENTIONS
- Chapter I, Subchapter H – INTERNAL REVENUE PRACTICE