Yes, it's profit. Even if you lined up the contractor and paid them in 2020, it's still profit. What you pay for the new roof just adds to the cost-basis of the structure and gets depreciated over the next 40 years. Depreciation doesn't start until the date/year you place the new asset "in service" as a business asset. So what you pay in taxes on it in 2020, you'll get back (in a sense) over the next 40 years as you depreciate the new roof.
