It's not an official registered business, it's just selling t-shirts and stuff. If a person sells something on eBay do they have to report that as business income?
In the United States, the money you make selling something is income and should be reported - included things sold on ebay, garage sales, etc.
You don't always have to report it as business income, but if it is not reported as business income it needs to be claimed as personal income.
Certainly isnt everywhere in the world, for one not every country has income tax. If you are selling your own second hand goods then in the UK it wouldnt be considered income as it is just liquidating your assets but if you are selling new goods or buying goods and then selling them on it is then income and must be declared no matter how high or low the amounts are - of cause if they are very low then there may be no tax due but it must be declared (UK)
If you live in the U.S. and you make over a certain amount, you may have to pay state taxes as well. The amount often varies from state to state. The nice thing about claiming your income as a business income is that you can deduct expenses. The bad thing about claiming your income as business income is that you need to pay social security tax, and that ain't cheap. If you don't make a profit after expenses over three years (I think this is right), your business is declared a "hobby," and you won't be able to use the income as business income. Check at irs.gov - if you can make out all the crap they have up there.