I have income that was reported on Form 1099-MISC, Box 7 (nonemployee compensation). I understand that if it is self-employment income, it should be reported on Schedules C and SE, and I would owe self-employment tax. However, I am not sure whether or not it should be considered self-employment income in my case.
In general, on what basis should I make this determination, and what criteria should I consider?
There is a note on the instructions for Form 1040 line 21:
Also, do not report on line 21 any nonemployee compensation shown on Form 1099-MISC (unless it isn't self-employment income, such as income from a hobby or a sporadic activity). Instead, see the instructions on Form 1099-MISC to find out where to report that income.
I think the income in my case might be from "sporadic activity", but I couldn't find any further information about how that term should be construed. There is no useful information in the Form 1099-MISC instructions.
In my specific case, the income was payment for participating in an academic research study. I am a university professor and the study was investigating the effectiveness of certain teaching methods that I used. I am not generally in the business of participating in such studies, so it seems to be that this might be "sporadic activity". However, the fact that it's closely related to my full-time work might complicate things; and I do not really know whether my interpretation would agree with the IRS's. I am not asking for tax advice on my specific situation, but I would particularly appreciate knowing about general principles that are likely to be relevant to me.