When does a hobby become a business? It sounds like a simple question to answer. But, that’s not always the case. The IRS has rules for what qualifies as a business, and your entrepreneurial idea might not be making the cut. Why should you know the difference between hobby and business? Whether your venture is a hobby or a business affects your tax liability. If the IRS declares it’s a hobby, you can’t deduct business losses and expenses on your tax return. You can only deduct your hobby expenses up to the amount of income you earn. Let’s say you want to start a T-shirt printing business. You spend $1,000 on a new screen printing press. In your first year, you only make $50 in sales. The IRS audits you and decides your company is a hobby. Hobby loss rules dictate that you can only deduct up to $50 you earned. If you deduct  business expenses  when you’re not a real company, you can get some heavy penalties. Treating a hobby tax deduction as a business tax deducti...