For 2009 and 2010, if you have a household employee, like a nanny or caregiver, you must declare them and pay payroll taxes on wages when they exceed $1,700 per year.

Selling online (such as via Ebay) is considered a taxable activity. If you are a 'casual seller', meaning you sell occasionally without intending to make a profit, you probably don't need to report the activity. If you are a more active seller, selling items at a profit or if you are selling collectibles, you must report the income either as a hobby or a business venture.