First, how did you complete your taxes in 2017 and 2018? It seems apparent to me that you did not use TurboTax.
You are required by law to depreciate rental property. No, you can't play "catch up" on your 2019 return. Generally, that first year depreciation amount will not be anywhere close to a full year's depreciation, because it's prorated based on the date placed in service.
I get the impression you placed the property in service sometime in 2017. If so, and you did not take depreciation then you *MUST* amend the 2017 tax return. Same for the 2018 tax return also.
Understand that you "MUST" amend your tax returns in chronological order starting with the oldest one first. That would be the 2017 tax return in your case if my above assumption is correct.
Understand also that it is *EXTREMELY* *RARE* for residential rental real estate to *EVER* have a taxable gain *on paper* when you do your taxes. Especially if you have a mortgage on the property. When in add up your rental expenses, property taxes, mortgage interest and the depreciation you are required to take by law, it will most likely exceed the amount of rental income received for the tax year.
So rental property will almost always operate at ever increasing losses that will get carried over and grow with each passing year.
Lets start with your 2017 tax return. First, confirm beyond any doubt that you did "NOT" depreciate the property on your 2017 tax return. To do that, look for IRS Form 4562. There will be a total of three 4562's for that specific rental property. Each will have a different title.
One prints in portrait format and is titled "Depreciation and Amortization" This is the one (and only one) that actually gets filed and sent to the IRS with your tax return every single year.
Two of them print in landscape format. Of those two, one is titled "Depreciation and Amortization Report" and the other is titled "Alternative Minimum Tax Depreciation" The *PRIMARY* one you need from your 2017 tax return is the one that prints in landscape format that is titled "Depreciation and Amortization Report".
