IRC Section 61
Gross Income v. Not Gross Income. Is the income taxable?

IRC Section 162
Trade or Business (Deductible v. Not Deductible).

IRC Section 1401
Rate & Applicability of Self-Employment Tax. Section 1402-Definitions.

IRC Section 2055
Transfer for Public, Charitable, and Religious Uses (Deductible v. Not Deductible).

IRC Section 3306
Definitions.

IRC Section 3402
Income Tax Collected at Source. Withholding taxes.

IRC Section 4401
Wagering Tax (Taxable v. Not Taxable). Gaming Issues.

IRC Section 4481
Use of Certain Vehicles Tax (Taxable v. Not Taxable). Highway Use Tax.

IRC Section 6041
Information at Source. Information Reporting.

IRC Section 7871
Indian Tribal Governments Treated as States for Certain Purposes.

IRC Section 7873
Federal Tax Treatment of Income Derived By Indians From Exercise of Fishing Rights Secured by Treaty, Etc.