Why does my tax return show me as self employed, paying self employment taxes if I am not? I am an employee who receives a W2 and does side work after my regular job.

If you are receiving a 1099NEC for the "side job" you are considered to be Self-Employed by the IRS.   You are required to pay self-employment tax for Social Security and Medicare, and you can prepare a Schedule C for your business expenses for that side job.

https://ttlc.intuit.com/questions/2926899-how-does-my-side-job-affect-my-taxes

https://ttlc.intuit.com/turbotax-support/en-us/help-article/form-1099-nec/1099-nec/L5qTsBiSe_US_en_US

https://ttlc.intuit.com/community/self-employed/help/how-do-i-report-income-from-self-employment/00/26653

https://ttlc.intuit.com/community/self-employed/help/what-is-the-self-employment-tax/00/25922

https://ttlc.intuit.com/questions/2902389-why-am-i-paying-self-employment-tax

https://ttlc.intuit.com/questions/1901340-where-do-i-enter-schedule-c

https://ttlc.intuit.com/questions/3398950-what-self-employed-expenses-can-i-deduct

https://ttlc.intuit.com/questions/1901110-do-i-need-to-make-estimated-tax-payments-to-the-irs

https://turbotax.intuit.com/tax-tools/calculators/self-employed/

What is work completed for resale?  1099NEC is for self employment work.  Here is a Turbo Tax FAQ Are you an employee or self employed?

https://ttlc.intuit.com/community/self-employed/help/am-i-an-employee-or-an-independent-contractor/00/26439

That sounds like self employment income.  you are the owner of your own self employment business.  You are in business for yourself.  Use your own info.  The people or company that pays you is your customer or client.  You are considered to have your own business for it.  YOU are the business.

You need to fill out schedule C for self employment business income and pay self employment tax in addition to regular income tax on it.  The SE tax is to pay Social Security and Medicare tax that wasn't taken out like on a W2.