Having home-based business means you can write off your Rent/Mortgage expenses??

Tweet

I heard from a very convincing source at work that if you have a home-based business, like on the computer or whatever, as long as the "room you do the business in" is in "proximity to a bathroom", then you can write off your rent expenses for tax season. And that an IRS representative is supposed to visit your house and verify it to make sure. Is this true or not? If yes: 1) I have two computers, a desktop in my bedroom and a laptop in the living room, I work on both. However, my bathroom is in proximity to my living room where my laptop is, so would that work? 2) Do sites like mylot, associated content, etc. all count in order to do this? Or would you simply need your own dot com site?