GI means all income from whatever source derived…
i. Differing formulas for computing GI are describe ion page 42 & 43.  Be sure to be aware of the distinctions btw the “labor/capital (Glenshaw Glass),” “accountant,” “economist/haig-Simons” formulas.
1. tax law/labor/capital(Glenshaw Glass):  the SC states that income includes: “undeniable accessions to wealth, clearly realized, and over which the taxpayers have complete dominion.”  Even thought this has become the accepted formula, it does not provide an adequate  answer to many income inclusion questions because it cannot be applied precisely to the multifarious circumstances that generate tax consequences.
2. economist/haig-simons formula:  person income is the algebraic sum of:
a. the market value of rights exercised in consumption &
b. the change in the value of the store of property rights between the beginning and the end of the period
i. This is not suitable for determining tax liability.
3. accountant formula:  encompasses only realized amount.  Assets that have been converted into money or other property by economic transactions such as sales or exchanges.
4. Note:  the big difference between the accountant and the labor/capital (Glenshaw Glass) is that Glenshaw Glass/tax law concept of income incorporates policy considerations in determining whether to tax an accession to wealth or whether to exclude it for gorss income.