Side job earnings for which you have no documentation are reportable on Schedule C. Using a Sch C means you are self employed, rather than employed by someone else. Your cash earnings are reportable even if you don't get a 1099, & you will pay self-employment taxes on the net earnings, which is what you have left after deducting your expenses for those odd jobs. Reporting it this way is usually the correct way, & will count as earned income so you might qualify for earned income credit. If you put large amounts of $ for odd jobs on line 21, Other Income, that does not count as "earned income" so you wouldn't get EIC, & the IRS might look at those numbers 1-2 years from now & notify you that you didn't report properly.
