A frustrating thing about working hard to earn money is knowing the IRS will tax a portion of your earnings. Federal taxable income generally includes wages, tips, royalties, commissions and for some, up to 85% of Social Security benefits. That's not an exhaustive list.
However, several types of income aren't taxable in the eyes of the IRS. Generally, whether income is taxable depends on various rules, requirements and regulations or whether you're talking about federal or state taxes.