No, you are required by federal law to depreciate rental property. Since you may not have done that for more than 3 years back, you can not use TurboTax to fix your error and correctly report the sale. But first, confirm beyond any doubt that you ahve "in fact" not depreciated the property.
Since you've been using TurboTax for the entire time it was a rental, more than likely you have been taking depreciation as required by federal law, and just don't realize it. The TTX program takes care of depreciation "for you" in the background, *provided* you set up things correctly in the program in the tax year you converted it to a rental.
Open the PDF copy of your 2018 tax return and look for the two IRS Form 4562's. Both forms will print in landscape format. One is titled "Depreciation and Amortization Report" and the other is "Alternative Minimum Tax Depreciation". You want to check the first one.
If you have the property itself along with all property improvements you may have done since converting it to a rental listed there, and there is a positive amount in the "prior year's depr" column showing the total of all depreciation taken before 2018, along with a positive amount in the "current year depr" column showing depreication for 2018, then you're good.
You can also check this in the 2019 TurboTax program *IF* you imported your data from the 2018 return.
In the rental property section for that specific property, elect to start/update the assets/depreication section. Then work through any assets listed there. A few screens in will show you prior year's depreciation already taken, and the last screen will show you the depreciation for 2019.
So confirm "beyond" "any" "doubt" that you did not depreciate the property. It's highly probable you did, and don't even realize it.
