How to prove my sales revenue to colleges?

I’m a freshman but have sold comic books on eBay for the past 2 years netting over 10k, eBay has records of the transactions and I do to. But, I never filed taxes on this money. How would a college know that i made this money?

You need to file your tax returns. Then when you apply to college and appy for financial aid, you will incluse those numbers in your paperwork.

if he did not earn enough in any one year to have to file with the IRS, there is no need for him to file taxes now.
$5500/ year is less than the legal requirement for filing taxes.

for 2017-
Without Filing 2017 Tax Return
Single Under 65 -$10,400

for 2018-

In 2018, for example, the minimum for single filing status if under age 65 is $12,000. If your income is below that threshold, you generally do not need to file a federal tax return.

Are you asking about financial aid or to show colleges that this is a worthy after school activity?
If the latter they will not ask for proof…

@menloparkmom - Would this be a self-employment gig? If so, then the OP needs to file and pay the self-employment taxes even though other state and federal taxes might not be owed.

MODERATOR’S NOTE:
Let’s move past the tax implications; that was not the OP’s question. A college AO will not ask for “proof.”

Ebay Seller: Sold over 500 comic books on ebay with revenue over 4 years of $10K. Kept track of orders, shipped promptly, managed customer questions while maintaining a rating of 4.9 stars.

Like any other EC, talk about what you did and what accomplished. You want to show colleges that you can stick with something, can be organized all while doing your school work.