No "percentage"---if you received earnings as an independent contractor the IRS sees you as self-employed even if you were paid in cash, received a 1099NEC, and/or did not have business name, license, etc,
https://ttlc.intuit.com/questions/2903027-how-do-i-report-income-from-self-employment
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
If your self-employment income was only from cash, personal checks, credit card payments, or cryptocurrency
Type Schedule C in the Search box and then select the Jump to link. This will take you to where you can enter any cash, personal checks, credit card payments, or cryptocurrency (Form 1099-K) related to your self-employment. You may first be asked some general questions about your business. After you answer them, you’ll be taken to the Let's get income for (your line of work) screen where you can enter this income as Additional Income.
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**
