It depends on the source of the income. Excess scholarship money is reported differently from money received for working.
The IRS generally considers undocumented cash income (no W-2 or 1099-NEC), for work performed, to be self employment income. You report the income from your own records. Enter at "Business Income & Expenses" and TurboTax (TT) will complete Schedule C for you and allow you to deduct any expenses associated with this income. You'll also have to pay self employment tax (social security & medicare tax) on any profits greater than $432.
There is a "one time gig" exception to reporting cash as self employment income, depending on the details of what you did, whether you have done it in the past and/or plan to do it again. Then it can be entered as other income.
