You have to pay income tax on the stipend. It is income to you. But you do not have to pay self-employment tax on it. It is not self-employment income. Here's how to enter a 1099-MISC with income in box 3 in TurboTax so that it is reported as "other income," and not as self-employment income.
TurboTax will now ask a series of questions about the 1099-MISC income. Answer as follows, even if some of the answers aren't true.
This will report the income as "other income" on Schedule 1 line 8 with the description "Other Income from box 3 of 1099-Misc."
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You can report it as other income on Sch 1 line 8. Here's how to enter it in TurboTax.
The income will be reported on Sch 1 line 8 with the description that you entered.