What must occur for income to be considered taxable?

For income to be considered taxable, there must be realization. This principle reflects the notion that income is not merely recognized for tax purposes when it is simply anticipated or expected, but rather when it has been realized through a completed transaction. Realization occurs when an individual receives income in a tangible form, such as cash, property, or services, and can be recognized as a permanent increase in wealth.

This principle is essential in tax law since it establishes the point at which income becomes taxable, rather than being concerned solely with the timing of when that income was earned. For example, if a business sells a product and receives payment, the income from that sale is realized and thus taxable, even if the payment is not received in the same calendar year.

The other options do not accurately capture the fundamental requirement for income to be taxable. While documentation and timing can be important for various tax considerations, they do not determine the realization principle that establishes taxability of income.