Which of the following is NOT included in gross income?

Child support payments are not included in gross income for federal tax purposes. The Internal Revenue Service (IRS) specifically excludes child support from gross income because these payments are considered non-taxable.

On the other hand, other income types listed, such as salary received, interest income, and rental income, are all part of gross income. Salary is treated as earned income, while interest income—generated from savings accounts, bonds, etc.—is considered unearned income. Rental income represents earnings from real estate and is also included in gross income. By identifying that child support payments do not fall into this category, one can better understand the nature of different income types and their tax implications.