Home Office Deduction Requirements

Hello,

My wife and I manage day to day operation of our rentals in Texas and California. We have been doing this for several years, but never deducted for use of our home as office. We do not have a registered business for this passive activity. We simply declare our income & expenses under our name as married filing jointly. I have couple of questions:

1) Must we have a registered business in order to deduct home office expenses, or can we take this deduction even without having a business entity?

2) We have been using TurboTax Premier to do our taxes. Will this software help enter home office deductions, or do we need to upgrade to a higher Turbotax version that supports businesses?