Chapter I - INTERNAL REVENUE SERVICE, DEPARTMENT OF THE TREASURY
- Subchapter A - INCOME TAX (§§ 1.1551-1 — 18.1379-2)
- Subchapter B - ESTATE AND GIFT TAXES (§§ 20.2031-7A — 26.7701-2)
- Subchapter C - EMPLOYMENT TAXES AND COLLECTION OF INCOME TAX AT SOURCE (§§ 31.0-1 — 36.3121)
- Subchapter D - MISCELLANEOUS EXCISE TAXES (§§ 40.0-1 — 157.7701-1)
- Subchapter F - PROCEDURE AND ADMINISTRATION (§§ 300.0 — 420.0-1)
- Subchapter G - REGULATIONS UNDER TAX CONVENTIONS (§§ 509.101 — 521.117)
- Subchapter H - INTERNAL REVENUE PRACTICE (§§ 601.101 — 801.8)