Cash earned for “under-the-table” jobs must be reported to the Internal Revenue Service as miscellaneous income, advises the IRS official website as of 2015. This includes cash earned from side jobs, prizes, awards, contest winnings and gambling proceeds. It also includes barter exchanges for services or goods.
IRS Publication 525 discusses taxable and nontaxable income in great detail. In most instances, all money, services and property received as income is taxable unless it is specifically exempted by the tax code, notes the IRS.
Self-employed taxpayers may not receive a 1099-MISC form for income that is less than $600 per year, but income of less than $600 is still taxable, advises the IRS. This income should be reported on Form 1040, Schedule C or Form 1040, Schedule C-EZ. Self-employment income is taxable, even if it is for babysitting or mowing lawns.