Rental real estate is depreciated for 27.5 years on a mid month convention. Most tax software will do the hard math for you as long as you plug in the right info. Your condo sounds like it might be a vacation home you rent out. If you use it personally for more then 15 days a year there are proration rules that apply to all the expenses including depreciation. The thing you have to determine is a good basis for the properties. Your basis is your investment in the properties. This includes, but is not limited to, your purchase price, some closing costs, improvements, and additions you may have made to either property. For the house, since it was your residence at one point, you must determine the lesser of your basis in the house on the date you converted it to a rental and the fair market value on that same day. That is your depreciable value for the house. You must also subtract the value of the land from the house and if there is any common land or common area value for the condo it must be subtracted.