Although it may be news to you that you “have a business” (and most of the other people who get their first 1099-NEC); The IRS considers anything on a form 1099-NEC to be self employment income. Enter the 1099 income, at Other Common income / income from a 1099-NEC . 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) on any profits greater than $432. These types of payments are frequently done this way. Your "employer" is not the only one.
On the other hand, If you do feel that you were an employee, TT gives you that option at the screen titled "Does one of these uncommon situations apply?"
Form 8919 is used to report wage income that was incorrectly reported on Form 1099. It will require you to pay FICA and Medicare taxes on the payments (remember - you would have paid them anyway if you were a w-2 employee) but not the matching employer share. You will also have to prepare Form SS-8 (a request for determination on employee vs. contractor status). You will probably also upset your employer, because the IRS may contact him about whether or not he properly paid wages. Form SS-8 is not in TT but is here: http://www.irs.gov/pub/irs-pdf/fss8.pdf
For more info See this IRS site ===>>> http://www.irs.gov/taxtopics/tc762.html
If you feel you qualify for the "one time gig" exception (see http://www.journalofaccountancy.com/Issues/2009/Jul/20091639.htm), you'll have to use a workaround in TT. Enter at the 1099-Misc screen, instead of 1099-NEC. Put the amount in box 3.
On the next screen Describe what the payment was for
On the next screen select "none of these apply"
On the next screen select "No it didn't involve work like my main job"
On the next screen select "I got it in 2020" ONLY
On the next screen select No, it didn't involve intent to earn money
TT will put the amount on line 8 of Schedule 1 as other income
