If you have net self employment income of $400 or more you have to file a schedule C in your personal 1040 return for self employment business income... so technically you DO have a business for tax purposes but you do not need to get/have an EIN ... skip the sections you do not need.
You may get a 1099-NEC for some of your income but you need to report all your income. So you need to keep your own good records. Here is some reading material……
IRS information on Self Employment….
http://www.irs.gov/Businesses/Small-Businesses-&-Self-Employed/Self-Employed-Individuals-Tax-Center
Publication 463, Travel, Gift, and Car Expenses
https://www.irs.gov/forms-pubs/about-publication-463
Publication 334, Tax Guide for Small Business
http://www.irs.gov/pub/irs-pdf/p334.pdf
Publication 535 Business Expenses
http://www.irs.gov/pub/irs-pdf/p535.pdf
