Originally Posted by FL370esq

Ironically, income is and has been defined for a very long time but, for Federal Tax purposes, the IRS and tax lawyers always turn to the touchstone case Commr. v. Glenshaw Glass Co., 348 U.S. 426 (1955), which is probably the most important case in American tax law in that it defined "income" quite broadly. Glenshaw Glass established that income is:

"Any undeniable accession to wealth,
which is clearly realized by the taxpayer, over which the taxpayer has complete dominion."

If you paint a farmer's barn and the farmer pays you for that service with meat from half a cow, the value of the meat is income.

The issue(s) revolve(s) around what part and how much of that income is either exempt or deductible under the Federal Tax code. That's where the CPAs and tax lawyers make their $$$. 😁