If you sell and buy articles on eBay in order to earn money, the IRS will likely classify your sales activities as a business. This means you will have to report net income from eBay sales. Report your total gross income on Schedule C, then reduce it to net income by subtracting the amounts you spent for allowable business-related expenses. This link should be helpful for you: https://turbotax.intuit.com/tax-tips/self-employment-taxes/a-tax-filing-factsheet-for-ebay-sellers/L...
In terms of how your business profit will affect financial eligibility, I would suggest you check with your educational institution or FAFSA, as there are numerous factors and various types or aid available.
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