be careful with this, a room cannot be consider even if 1% of it is used for dual purposes. For example if you have an office but you use it as a child nursery too. 80% of your dwelling is going to raise a red flag.

Second, if you are going to be freelancing you need to file for an S-Corp it helps you to opt out of some taxes. It will lower your effective tax rate because it get's rid of some of the FICA tax and because it allows you to take some of the earned income and transfer it over to capital gains.

You also really need to go to a good CPA, they cost around $300 to $600 and they will save you far more than that. The first year I went to a CPA they saved me 10k from the best I could do on my own. Not getting a CPA while freelancing is throwing money away. It is the quickest thing you can do to improve your bottom line.