It depends on your location. In Canada, where I am, you're supposed to pay taxes on any money you make, even if it's $100 but you're not required to be registered as a business until you're making $30,000 or more from it. Laws are kinda dumb here, you're supposed to pay taxes on money made at a garage sale but let's face it; who does that? I don't want to give advice that may be encouraging of breaking the law so I won't add my personal opinion on the subject but let's just say that I didn't make any money off of the clutches I had this year. I did trades for all my 2013 babies, and didn't gain anything in terms of monies from my hobby breeding. If you're advertising as a business and you're putting yourself out there - it's in your best interest to register and pay the taxes. The last thing you want is an audit to rule not in your favor. I'm waiting until 2014 to register and start making actual money transactions.