[mvpel]

Sources of income are not taxed; the income ITSELF is taxed.

Actually, only "taxable income" is taxed. And the regulations set forth a list of operative sections which require the determination of taxable income from specific sources and activities, and Section 861 in general is used to determine the sources of income for the purpose of the income tax.

[Poohbah]

Actually, only "taxable income" is taxed.

And "taxable income" is defined as "gross income minus allowed deductions and exemptions," which are spelled out in the tax code.

And the regulations set forth a list of operative sections which require the determination of taxable income from specific sources and activities, and Section 861 in general is used to determine the sources of income for the purpose of the income tax.

Please provide contextual citations for ALL references to Section 861 in the Internal Revenue Service regulations.